Answer and Explanation:
A consumer surplus is the gain a consumer makes by paying less than he is willing to pay for a product. Example if a consumer is willing to pay $300 for a mobile phone but pay $200 for the phone, the consumer surplus is $100
Given that the demand function is P=60-Q
And price is 30
Therefore consumer surplus is, substitute 30 in p
30=60-Q
30-60=-Q
-30=-Q
Q=-30/-1
Q=30
Therefore consumer surplus = 30