sum of reciprocals means 1/x+1/y=2/5 subsitute x=5y for x in 1/x+1/y=2/5 and get 1/5y+1/y=2/5 multiply 1/y by 5/5 to make it 5/5y so you can add since the denomenators (bottom number) are the same
1/5y+5/5y=2/5 6/5y=2/5 multiply both sides by 5y 6=2y divide both sides by 2 3=y put this into x=5y so x=5(3) x=15 y=3
