Victor bought $8.40 worth of stamps. He bought 3 times as many $.17 stamps as $.25 stamps and 4 times as many $.02 stamps as $.25 stamps. Find the number of $.25 stamps he purchased.

Victor bought $8.40 worth of stamps. He bought 3 times as many $.17 stamps as $.25 stamps and 4 times as many $.02 stamps as $.25 stamps. Find the number of $.25 stamps he purchased.