If D varies jointly as the square of E and F, and D = 210 , when E = 32 and F = 70

Answer 1

D = k(EF)^2
when D = 210, E = 32 , and F = 70
210 = k(32*70)^2
210 = k(5017600)
k = 3/71680

D = (3/71680)(EF)^2

so , now what?