Discussion Forum

What number should be subtracted from 3, 5, 6, 7 so that the resulting numbers in this order form a proportion?

Answer:

Explanation:

Let the number $x$ be subtracted from each given number

$\frac{3-x}{5-x}=\frac{6-x}{7-x}$

$\Rightarrow (3-x)(7-x)=(6-x)(5-x)$

$x^{2}-10x+21$ $=x^{2}-11x+30$

$\Rightarrow x=30-21$ $=9$