Question 263752
There is an error in a solution provided by another tutor. It is correct up to:
{{{4x^2 = 20x}}}
This is a quadratic equation. We should get one side equal to zero (by subtracting 20x from each side:
{{{4x^2 - 20x = 0}}}
Factor:
{{{4x(x - 5) = 0}}}
And use the Zero Product Property which tells us that this product is zero if one  of the factors is zero:
{{{4x = 0}}} or {{{x - 5 = 0}}}
Solving these we get:
{{{x = 0}}} or {{{x = 5}}}
For x = 0, the other number is 4x = 4(0) = 0.
For x = 5, the other number is 4x = 4(5) = 20.
So the two numbers are (0 and 0) or (5 and 20).