Given that consumption in the two periods of life are perfect complements, so that c and ci are related as c. = ac. Use the intertemporal budget constraint, as expressed in equ. (9.11), to show how equations (9.13) and (9.14) are derived algebraically c + = we, (9.11) 1+r we(1 + r) C = (9.13) 1+rta c'= awe(1 + r) (9.14) 1+rta