<h2>
Good morning,</h2>
<em><u>__________________</u></em>
<em><u>Answer</u></em>:
a+a+a = 3a.
4b-b = 3b.
3x²+x² = 4x².
<u><em>explanation</em></u>
a+a+a = 3a.
4b-b = b(4 - 1) = b × 3 = 3b.
3x²+x² = x²(3 + 1) = x² × 4 = 4x².
_______________________________
:)
Using a calculator, you can find out that

and so that means

so your answer is
4/5 -3/7=
28/35 -15/35
=13/35