Math help needed

Question

3 3/15+  4 2/5=?

 

7 1/2- 6 3/10=?

 

6-3 1/4=?

 

a+1/3= 6/7 

 

Joseph had 7 1/4 ounces of candy to share with his friends. He gave them 2 4/5 ounces of candy over to play video games. How many ounces of candy does Joseh have left. Please explain the steps in solving this

 

 

 

 Please help me solve these. Please

Answer 1

3 ³/₁₅ + 4 ²/₅

= (3+4) + (³/₁₅ + ²/₅)

= 7 + (³/₁₅ + ⁶/₁₅)         [Put 3/15 and 2/5 over a common denominator = 15]

= 7 ⁹/₁₅

= 7 ³/₅

 

7 1/2 - 6 3/10

=(7-6) + (1/2 - 3/10)

= 1 + (5/10 - 3/10)          [Put 1/2 and 3/10 over a common denominator = 10]

= 1 + 2/10

= 1 ¹/₅

 

6 - 3 ¹/₄

= (6 - 3) + (0 - 3/4)

= 3 - 3/4

= 2 ¹/₄

 

a + ¹/₃ = ⁶/₇

a = 6/7 - 1/3                    [Subtracted 1/3 from both sides]

a = 18/21 - 7/21               [Put 6/7 and 1/3 over a common denominator = 21]

a = ¹¹/₂₁

 

The last problem seems to be missing some information.  How many friends did he share his candy with?

 

 

Answer 2

Hi Taryn--

 

with each of these equations, the first thing you need to do is find the common denominator of the 2 fractions. Do you already know how to do that?

 

[if you know already, skip this part. if not, here's how to find the common denominator: when you have two fractions with different denominators, they can't "speak the same language" until you make the denoms the same. You do that by taking the two denominators and finding their least common multiple. You can find a common multiple either by just multiplying the denoms together, or by listing out their multiples until you find one they both have. That will be your common denominator. When you change the original denominator to the new common one, you do it by multiplying, and whatever you multiply the denom by, you also have to multiply the numerator by. Don't worry if that's confusing--let's look at one of your questions...]

 

OK, so on the first question, you have denominators of 15, and 5. Luckily, 15 is a multiple of 5, so you can leave the 15, and change the 5 to a 15, which you do by multiplying the 5 TIMES 3. And since you multiplied the bottom by 3, you have to do the same to the numerator, which in this case is 2.

 

So instead of 4 2/5, it's now 4 6/15

 

You can add 3 3/15 + 4 6/15, and you get ... 7 9/15. If you're being picky, simplify the 9/15 to 3/5...

 

You should be able to apply the same rules to the next one--find the common denominator, then whatever you do the bottom to GET to that common denominator, also do it to the top. (Don't forget that the second question is subtraction, but the common denom rules are the same.)

 

I'm going to post this, then post a second answer for the next questions...

Answer 3

Taryn, I am going to give you some examples and see if you can figure it from there.  I bet you can!

 

6 1/2 + 5 1/5

 

We first have to find a common denominator, which means finding the LCM of 2 and 5, which is 10.

 

1/2 = 5/10, right?  1/5 = 2/10, right?

 

Here's another:  7 1/2 - 6 4/7

 

Here, the LCM of 2 and 7 is 14.  1/2 = 7/14 and 4/7 = 8/14.

 

7 7/14 - 6 8/14

 

We can't do 7 - 8!  So, we borrow 14/14 from the 7 (since 14/14 = 1) and add it to the 7/14.  Our 7 7/14 now becomes 6 21/14.  Still good?

 

Now, 6 21/14 - 6 8/14 = 13/14

 

Hope this helps!