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(3/5 + 3/4)-1/2

need help just in the process of the prblom

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Jack W. | I can make learning funI can make learning fun








do any problem in this order to get the answer,

the answer to yours is 17

you have to get the bottom parts the same

like multiply all the numbers to get 20

your least common ddenominator 

so you multiply tithe first fraction by 4 to get 20 on the bottom

but the second by 5 to get 20 on the bottom

so you get 12/20+15/20

then you add those to get 27/20-10/20

your answer is 17/20

name is John



Chelsea P. | General Biology and Geology Courses, also familiar with AdobeGeneral Biology and Geology Courses, als...

Hi Kimberly,

The first thing to remember is the order of operations to solve the problem.  The mnemonic device I like to remember the order is Please Excuse My Dear Aunt Sally - which stands for Parentheses, Exponents, Multiplication, Division, Addition, then Subtraction.  So first, you start with what is within the parentheses:  3/5+3/4.  To add two fractions, you have to make the denominators (lower parts) of the fractions equal to each other (called finding the lowest common denominator).  

The easiest way to find this is to multiply the denominators together.  5 * 4 = 20, so this will be our new denominator.  Let's start with the first fraction: 3/5.  We got the denominator of 5 to equal 20 by multiplying the bottom number by 4, so now we must also multiply the top of the fraction (3) by 4.  3 * 4 = 12, so the new fraction we are going to use, then, is 12/20.  Then we do the same to the second fraction - we multiplied the denominator of 4 by 5 to get the common denominator 20, so now we must do the same to the top number - 3*5=15, so the new fraction is 15/20.  Now we take the two fractions we just made, 12/20 and 15/20, and add them together.  Since the denominators are now the same, you just have to add the two numerators, and 12+15=27.  This makes it so that 3/5 + 3/4 = 12/20 + 15/20 = 27/20.

Now that the parentheses are solved for, you must subtract 1/2 from 27/20.  Again, you do this by finding the least common denominator.  You can get 20 from 2 by multiplying it by 10, so multiply both the top and bottom of the fraction by 10, which equals 10/20.  Now you can subtract: 27/20 - 10/20 = 17/20.  The answer is 17/20.

John R. | Patient, caring elementary tutor for all subjects and students.Patient, caring elementary tutor for all...
4.6 4.6 (5 lesson ratings) (5)

Remember PEMDAS: Parentheses, Exponents, Multiplication and Division (left-to-right), Addition and Subtraction (left-to-right).  First find the LCD of 3/5 and 3/4, which is 20. This becomes 12/20+15/20 = 27/20.  Then, do 27/20 - 1/2, again finding the LCD first, which is 20. This becomes 27/20 - 10/20 = 17/20, or .85

Chantal T. | College Bound Tutor AvailableCollege Bound Tutor Available

Hi, Kimberly! In order to solve this problem you will have to:

-find a common denominator (bottom number of the fraction) 

   what number does each go into? 20 (x/20)

-multiply each fraction so that all of the denominators are the same 

   5*?=20 (4); 3*4=12; 12/20

   4*?=20 (5); 3*5=15; 15/20

   2*?=20 (10); 1*10=10; 10/20

-plug your information back and start using the order of operations

   (12/20 + 15/20) - 10/20

   12/20 + 15/20 = 27/20

   27/20 - 10/20 = 17/20

-Reduce if possible and you have your answer

   no reduction is needed; your answer is 17/20