-a(-23-5a)=3

Solution for -a(-23-5a)=3 equation:

-a(-23-5a)=3

We move all terms to the left:

-a(-23-5a)-(3)=0

We add all the numbers together, and all the variables

-a(-5a-23)-3=0

We multiply parentheses

5a^2+23a-3=0

a = 5; b = 23; c = -3;
Δ = b2-4ac
Δ = 232-4·5·(-3)
Δ = 589
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(23)-\sqrt{589}}{2*5}=\frac{-23-\sqrt{589}}{10}
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(23)+\sqrt{589}}{2*5}=\frac{-23+\sqrt{589}}{10}
$