Cross multiplication! Because it is a proportion [tex] \frac{2}{3} [/tex] = [tex] \frac{?}{48} [/tex] 2 × 48 = 3 × ? 96 = 3 × ? Divide by 3 on both sides to isolate the unknown number [tex] \frac{96}{3} [/tex] = [tex] \frac{3 * ?}{3} [/tex] 3 and 3 cancels out