Question

In the equality 5/? = ?/20, if each ? Represents the same number, then ? Must equal :

Answer 1

? = 10

Explanation:

Let " ? " be x.

5 / x = x / 20

x * x = 5 * 20

x² = 100

[ 100 = 10 x 10 = 10² ]

x² = 10²

x = 10