10x - 35 + 3ax = 5ax - 7a Subtract 3ax from both sides
10x - 35 = 2ax - 7a Factor a out of the right side
10x - 35 = a (2x - 7) Divide both sides by (2x - 7)
[tex] \frac{10x - 35}{2x - 7} [/tex] = a Switch the sides to make it easier to read
a = [tex] \frac{10x - 35}{2x - 7} [/tex]