The graph of a linear equation with two variables, x and y, is a line. There are an infinite number of solutions for a line
You can use z = x², then rewrite the equation as
4z²-21z+20 = 0
This factors as
(4z-5)(z-4) = 0
so has solutions
z = 5/4, 4
The solutions for x are then
x = ±√z = {-2, -(√5)/2, (√5)/2, 2}
Actually none of the answers is correct - it's neither 30,900 nor 40,000.
30,944 rounded to the nearest ten thousand will give us 30,000. It's because 30,944 is closer to 30,000 than to 40,000.
4 i think when its not simplified.