Question

I just need help on how to approach this problem.

Answer 1

\[\frac{ 3a-4 }{ 5 }+\frac{ 7a-2 }{ 15 }-\frac{ 4a+7 }{ 10 }\]

Answer 2

you need to find the common denominator for 5, 15 and 10

one way is factor each into prime factors:
5 = 5
15 = 3*5
10 = 2*5

in the right column you see you need a 5, a 3 and a 2. so try 5*3*2= 30

Answer 3

to change the 5 in the bottom of the 1st fraction into 30, multiply both the top and bottom by 6 (6/6 is 1 so the fraction's value remains the same)
you get
\[ \frac{(3a-4)\cdot 6}{5\cdot 6} \]
the bottom is 30 just like you want
distribute the 6 in the top. That means multiply 6 times each term inside the parens
\[ \frac{(6\cdot 3\cdot a-6\cdot 4)}{30} \]

Answer 4

the first fraction becomes
\[ \frac{18a -24}{30} \]

do the same for the other fractions
once they all have 30 as a denominator, you can add the tops together

Answer 5

Thank you so much! I did all the steps you did and got
\[\frac{ 20a-49 }{ 30}\]

It said it was the right answer. Thanks for the help :P