The answer is 5 because 5x4=20 divided by 100
F(x) = 3x + 1
let f(x) = y
y = 3x + 1
y - 1 = 3x
3x = y - 1
x = (y - 1)/3
From y = f(x), x = f⁻¹(y)
<span>x = (y - 1)/3
</span>
f⁻¹(y) = (y - 1)/3
f⁻¹(7) = <span>(7 - 1)/3 = 6/3 = 2
</span>f⁻¹(7)<span> = 2</span>
By the Pythagorean theorem,
{[(8 - 3) * 2] + [(5 * 6) - 5]} / 5 =
= {[2 * 8 + 2 * (-3)] + 30 - 5} / 5 =
= [(16 - 6) + 25] / 5 =
= (10 + 25) / 5 =
= 35 / 5 =
= 7
Brackets make it look complex but it's not that bad at all :)
