x+2x+5+3x(2x+5)=65

Solution for x+2x+5+3x(2x+5)=65 equation:

x+2x+5+3x(2x+5)=65

We move all terms to the left:

x+2x+5+3x(2x+5)-(65)=0

We add all the numbers together, and all the variables

3x+3x(2x+5)-60=0

We multiply parentheses

6x^2+3x+15x-60=0

We add all the numbers together, and all the variables

6x^2+18x-60=0

a = 6; b = 18; c = -60;
Δ = b2-4ac
Δ = 182-4·6·(-60)
Δ = 1764
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1764}=42$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(18)-42}{2*6}=\frac{-60}{12}
=-5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(18)+42}{2*6}=\frac{24}{12}
=2
$