So since your equation has x in miles, then change 3 and 4 from feet to miles by dividing them by 5280. then input each of those numbers into your formula. example: 1. W = (190 * 4000^2)/ (4000 + 100)^2
if you are curious, your equation is derived from this: F(g) = G (m1)(m2)/(r^2) where m1 and m2 are the two masses (the earth and the person) and r is the distance between, from center to center.
