(4t+16)(5t-21)=360

Solution for (4t+16)(5t-21)=360 equation:

(4t+16)(5t-21)=360

We move all terms to the left:

(4t+16)(5t-21)-(360)=0

We multiply parentheses ..

(+20t^2-84t+80t-336)-360=0

We get rid of parentheses

20t^2-84t+80t-336-360=0

We add all the numbers together, and all the variables

20t^2-4t-696=0

a = 20; b = -4; c = -696;
Δ = b2-4ac
Δ = -42-4·20·(-696)
Δ = 55696
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{55696}=236$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-4)-236}{2*20}=\frac{-232}{40}
=-5+4/5
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4)+236}{2*20}=\frac{240}{40}
=6
$