Question

（70+X）除以（350+X）=30%这道方程该如何解?

Answer 1

（70+X）除以（350+X）=30%

70+X=0.3(350+X)

70+X=0.3×350+0.3X

X-0.3X=105-70

0.7X=35

X=35÷0.7

X=50