Two ladders crisscross an alley of width W. Each ladder reaches from the base of one wal...

Two ladders crisscross an alley of width W. Each ladder reaches from the base of one wall to some point on the opposite wall. The ladders cross at a height H above the pavement. Find W given that the lengths of the ladders are x₁ = 20 ft and x₂ = 30 ft, and that H = 8 ft.