(140-y)y=140

Solution for (140-y)y=140 equation:

(140-y)y=140

We move all terms to the left:

(140-y)y-(140)=0

We add all the numbers together, and all the variables

(-1y+140)y-140=0

We multiply parentheses

-1y^2+140y-140=0

a = -1; b = 140; c = -140;
Δ = b2-4ac
Δ = 1402-4·(-1)·(-140)
Δ = 19040
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{19040}=\sqrt{16*1190}=\sqrt{16}*\sqrt{1190}=4\sqrt{1190}$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(140)-4\sqrt{1190}}{2*-1}=\frac{-140-4\sqrt{1190}}{-2}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(140)+4\sqrt{1190}}{2*-1}=\frac{-140+4\sqrt{1190}}{-2}
$