problema 4 va roggggg!

2(5a+3b)=3a+2b
10a+6b=3a+2b
7a=-4b
a=-4/7b
(a+b)/(a-b)= (-4/7b+b)/(-4/7b-b)
=(-4/7b+7/7b)/(-4/7b-7/7b)
=3/7b / (-11/7b)
=3b/7 × 7/-11b
=3/-11