In the equation $x(9x - 2a) + b(9x - 2a) - (x + b) = 0$, $a$ and $b$ …

Question

Prompt

In the equation

x (9 x - 2 a) + b (9 x - 2 a) - (x + b) = 0

a

and

b

are positive constants. A solution to the equation is

x = 42

. What is the value of

a