Question

Brad says that if a second number is 125% of the first number, then the first number must be 75% of the second number. Is he correct?

Answer 1

Answer: He is not correct.

Steps:

Let x1 and x2 be the first and second number, respectively.

$x_2 = \frac{5}{4}x_1\\\frac{4}{5}x_2 =x_1$

In words, if the second is 125%, or 5/4 of the first number (first equation),

then the first is 4/5 of the second, which is 0.8 or 80%.