Barney and Robin went shopping at H&M. The store was having a sale on all shirts and pants. Barney spent $70 on 3 shirts and 2 pants and Robin bought 1 shirt and 4 pairs of pants for $90.Write an equation to describe the total spent by Barney in terms of the numbers of shirts and pants purchased. Let x be the price of a shirt and y be the price of a pair of pants.