(7d-9)(5d-3)=0

Solution for (7d-9)(5d-3)=0 equation:

(7d-9)(5d-3)=0

We multiply parentheses ..

(+35d^2-21d-45d+27)=0

We get rid of parentheses

35d^2-21d-45d+27=0

We add all the numbers together, and all the variables

35d^2-66d+27=0

a = 35; b = -66; c = +27;
Δ = b2-4ac
Δ = -662-4·35·27
Δ = 576
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{576}=24$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-66)-24}{2*35}=\frac{42}{70}
=3/5
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-66)+24}{2*35}=\frac{90}{70}
=1+2/7
$