Example
Alice loves chocolate (X) and strawberries (Y). Her utility is $$u \left( X, Y \right) = X \times Y$$
If Alice has 2 chocolates bars and 1 strawberry, she gets utility $$u \left( 2, 1 \right) = 2 \times 1 = 2$$
Question
Alice loves chocolate (X) and strawberries (Y).
Her utility function is `u (X, Y) = XY`.
What is her utility for 4 chocolate bars and 3 strawberries?
For 4 chocolate bars and 3 strawberries, Alice's utility is $$ u \left( 4, 3 \right) = 4\times3 = 12 $$