(2x-1)/(2x+2)=7/10

First, do $\frac{7}{10} \cdot 2x+2$ and this is cross multiplying! Now multiply this out and solve for x.

(2x - 1) / (2x + 2) = 7 / 10

2x - 1 * 10 = 2x + 2 * 7

20x - 10 = 14x + 14

20x - 14x = 14 + 10

6x = 24

x = 4