Martina buys a video game that normally costs d dollars, but it is on sale for 25% off. If the sales tax on the game is 8%, how much does Martina pay for the game?

25% off means that they are paying 75% of the original price. Multiply d by 75%:

0.75d

Now you need to multiply the price by 1 plus the sales tax to get the total cost:

0.75d x 1.08

Simplify by multiplying 0.75 by 1.08 to get:

0.81d