Answer
-3
Work Step by Step
For cross multiplication, we know:
$$\frac{a}{d} =\frac{b}{c} \rightarrow ac=bd$$
Thus, we find:
$$3\left(x-7\right)=5x\cdot \:2\\ 3x-21=10x\\ x=-3$$
Checking our solution by plugging $-3$ back into the equation, we assure that the solution checks out.
