Question

A stack of one hundred fifty cards is placed next to a ruler, and the height of the stack is measured to be 5/8 inches.

Answer 1

Divide 5/8 by 150, to see how thick each is, that'll give you 150 even pieces that add up to 5/8

$\bf \cfrac{\frac{5}{8}}{150}\implies \cfrac{\frac{5}{8}}{\frac{150}{1}}\implies \cfrac{5}{8}\cdot \cfrac{1}{150}\implies \cfrac{1}{8\cdot 30}\implies \cfrac{1}{240}$