5. LO 2,5 A consumer receives income y in the current period and income y in the future period, and pays taxes of t and t in the current and future periods, respectively. The consumer can borrow and lend at the real interest rate r. This consumer faces a constraint on how much he or she can borrow, much like the credit limit typically placed on a credit card account. That is, the consumer cannot borrow more than x, where x