Suppose that a consumer's total benefit is $4 for consuming one cup of ice cream and $7 for consuming two cups of ice cream. the consumer's willingness to pay for the second cup of ice cream is

Consumers total benefit for consume one cup = $4

and $7 for second cup of ice cream

how much consumer will pay for second cup = ? = x

x = consumer money for second cup - consumer money for first cup

x = $7 - $4

x = $3

so, consumer's willingness to pay for the second cup of ice cream is $3.