(X)x(7/9)=140

Solution for (X)x(7/9)=140 equation:

(X)X(7/9)=140

We move all terms to the left:

(X)X(7/9)-(140)=0

We add all the numbers together, and all the variables

XX(+7/9)-140=0

We multiply parentheses

7X^2-140=0

a = 7; b = 0; c = -140;
Δ = b2-4ac
Δ = 02-4·7·(-140)
Δ = 3920
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{3920}=\sqrt{784*5}=\sqrt{784}*\sqrt{5}=28\sqrt{5}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-28\sqrt{5}}{2*7}=\frac{0-28\sqrt{5}}{14}
=-\frac{28\sqrt{5}}{14}
=-2\sqrt{5}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+28\sqrt{5}}{2*7}=\frac{0+28\sqrt{5}}{14}
=\frac{28\sqrt{5}}{14}
=2\sqrt{5}
$