we suggest this system equations: xy/2=64 x=2y we solve this system by substitution method: (2y)y/2=64 y²=64 y=⁺₋√64 Then, we have two solutions: y₁=-8; invalid solution y₂=8; ⇒x=2y=2*8=16:
There are 5280 feet in a mile 45 * 5280 = 237600 there are 3600 seconds in an hour (60 minutes time 60 seconds) so we have 237600 feet in 3600 seconds 237600 / 3600 = 66 feet per second.