A jar has five different colors of gumballs in it. 20% of the gumballs are blue. There are 10 more green gumballs than blue ones. There are half as many red gumballs as blue ones. The ratio of the number of red gumballs to the number of yellow gumballs is
4:7. If the remaining 27.5% of the gumballs are white, and one fifth of them were replaced by yellow ones, how many yellow gumballs are there?