(p^3 r^2 - q^4) / (0.5^2) for p = 4/5, q = 1.4, r = -6

[Tiana]

p^3 r^2 - q^4
.5^2


p=4/5 q=1.4 r=-6

[Denis]

p^3 r^2 - q^4
.5^2
p=4/5 q=1.4 r=-6
1.4 = 1 4/10 = 1 2/5 = 7/5

so you have: [(4/5)^3 * (-6)^2 - (7/5)^4] / (.5)^2

let's see where you are: what is (4/5)^3 ?