Shelly's preferences for consumption and leisure can be expressed as

U(C, L) = (C - 100) (L - 40).

This utility function implies that Shelly's marginal utility of leisure is C - 100 and her marginal utility of consumption is L - 40. There are 110 (non-sleeping) hours in the week available to split between work and leisure. Shelly earns $10 per hour after taxes. She also receives $320 worth of welfare benefits each week regardless of how much she works.

Find Shelly's optimal amount of consumption and leisure?