15=18x^2+15x-10

Solution for 15=18x^2+15x-10 equation:

15=18x^2+15x-10

We move all terms to the left:

15-(18x^2+15x-10)=0

We get rid of parentheses

-18x^2-15x+10+15=0

We add all the numbers together, and all the variables

-18x^2-15x+25=0

a = -18; b = -15; c = +25;
Δ = b2-4ac
Δ = -152-4·(-18)·25
Δ = 2025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2025}=45$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-45}{2*-18}=\frac{-30}{-36}
=5/6
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+45}{2*-18}=\frac{60}{-36}
=-1+2/3
$