(2,5x-7)(8x-9,6)=0

Solution for (2,5x-7)(8x-9,6)=0 equation:

(2.5x-7)(8x-9.6)=0

We multiply parentheses ..

(+16x^2-19.2x-56x+67.2)=0

We get rid of parentheses

16x^2-19.2x-56x+67.2=0

We add all the numbers together, and all the variables

16x^2-75.2x+67.2=0

a = 16; b = -75.2; c = +67.2;
Δ = b2-4ac
Δ = -75.22-4·16·67.2
Δ = 1354.24
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-75.2)-\sqrt{1354.24}}{2*16}=\frac{75.2-\sqrt{1354.24}}{32}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-75.2)+\sqrt{1354.24}}{2*16}=\frac{75.2+\sqrt{1354.24}}{32}
$