603=62.8r+6.28*r2

Solution for 603=62.8r+6.28*r2 equation:

603=62.8r+6.28r^2

We move all terms to the left:

603-(62.8r+6.28r^2)=0

We get rid of parentheses

-6.28r^2-62.8r+603=0

a = -6.28; b = -62.8; c = +603;
Δ = b2-4ac
Δ = -62.82-4·(-6.28)·603
Δ = 19091.2
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-62.8)-\sqrt{19091.2}}{2*-6.28}=\frac{62.8-\sqrt{19091.2}}{-12.56}
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-62.8)+\sqrt{19091.2}}{2*-6.28}=\frac{62.8+\sqrt{19091.2}}{-12.56}
$