1. (5%) Suppose a consumer with a monthly income of $600 is choosing from the following mobile phone plans to maximize his utility.

Plan 50: $50 per month to use up to 300 units per month, $0.5 for each additional unit beyond 300 units, and $0.2 for each additional unit beyond 500 units.

Plan 80: $80 per month to use up to 600 units per month and $0.4 for each additional unit beyond 600 units.

Illustrate in a figure a case in which the consumer is better off choosing Plan 80.