A=8x^2+30x

Solution for A=8x^2+30x equation:

=8A^2+30A

We move all terms to the left:

-(8A^2+30A)=0

We get rid of parentheses

-8A^2-30A=0

a = -8; b = -30; c = 0;
Δ = b2-4ac
Δ = -302-4·(-8)·0
Δ = 900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{900}=30$
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-30)-30}{2*-8}=\frac{0}{-16}
=0
$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-30)+30}{2*-8}=\frac{60}{-16}
=-3+3/4
$