Clarisse, a self-confessed sweet tooth, regularly consumes chocolates and doughnuts. Her utility function is U(x_C,x_D)= x_Cx_D where xC and xD denotes quantity for chocolates and doughnuts, respectively. The unit price per chocolate is R15 and per doughnut is R10, while Clarisse's income allocation is R60 a day. The price per doughnut suddenly falls to R6.

Question:

1.1 Derive Clarisse's demand functions for chocolates and doughnuts. [5]

1.2 Derive, with supporting mathematical techniques, the Slutsky income effect and substitution effect of the price change from the demand functions derived in 1.1. [7]