On the left side of the equation, x is being multiplied by 0, which makes the left side equal to zero.

0 = (10 * 50) - (10 * 4x)

0 = 500 - 40x

Add 40x to both sides

0 + 40x = 500 - 40x + 40x

40x = 500

Divide both sides by zero

40x/40 = 500/40

**x = 12.5**