solve rartional expression

[x/5x+10] + [x-3/x+2]= [7/5] is the answer -8

no, subbing it in would show you that it does not work.

hint:
x/[5(x+2)] + (x-3)/(x+2) = 7/5

isn't the lowest common denominator 5(x+2) ?
multiply each term by that