(-3m+8)(-5m+4)=0

Solution for (-3m+8)(-5m+4)=0 equation:

(-3m+8)(-5m+4)=0

We multiply parentheses ..

(+15m^2-12m-40m+32)=0

We get rid of parentheses

15m^2-12m-40m+32=0

We add all the numbers together, and all the variables

15m^2-52m+32=0

a = 15; b = -52; c = +32;
Δ = b2-4ac
Δ = -522-4·15·32
Δ = 784
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{784}=28$
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-52)-28}{2*15}=\frac{24}{30}
=4/5
$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-52)+28}{2*15}=\frac{80}{30}
=2+2/3
$