is my answer for this problem right? PLEASE ANSWER IN 24 HOURS

Question

I will show the steps i used, if you could check them and tell me if i am correct or not.

3/8h+7/12=3/4

3/8h+7/12-12/7=3/4-12/7

8/3*3/8h=9/3*8/3

h=8/14=4/7

 

Answer 1

Sorry, good try.  What you need to do is to find a common denominator for the fration 3/8, 7/12 and 3/4.  Common denominator is what will divide equally into each fraction.  In this case, it is 24. 

1)  Convert all three fractions into denominators with 24.

 

3/4 = x/24     4 goes into 24 - 6 times (6 x 4 = 24).   multiply 6 by 3 (numerator) = 18/24.

7/12 = y/24    12 goes into 24 - 2 times (2 x 12 = 24).  multiply 2 by 7 (numerator) = 14/24

3/8 = z/24    8 goes into 24 - 3 times (8 x 3 = 24), multiply 3 by 3 (numerator) = 9/24

 

Now you have 9/24h + 14/24 = 18/24

 

2) subtract 14/24 from each side

 

9/24 h + 14/24 - 14/24 = 18/24 - 14/24

 

9/24 h = 4/24

 

Now you can divide by 24/9 on both sides (to get the [h] by itself)

 

24/9 divided by 9/24 h = 4/24 divided by 24/9

 

the 24/9 and 9/24 cancel each other out on the left side

 

h = 4/9   (24 cancels out on the right side)

 

about above the reciprical of a fraction can NOT be used to cancel it out by plus/minus.  In order to do plus/minus on fractions a COMMON DENOMINATOR MUST BE USED.  

 

ie you can't say 7/12 - 12/7 = 0.  7/12 and 12/7 can only be used to cancel out when you MULTIPLY fractions as I did with 24/9 and 9/24 above.