Final answer:
Bruce will pay $68 for the chalkboard during the sale.
Step-by-step explanation:
To find out how much Bruce will pay if he buys the chalkboard during the sale, we need to know the discount percentage. Let's say the discount is 20%. To calculate the sale price, we subtract the discount amount from the original price.
The discount amount is calculated by multiplying the original price by the discount percentage. In this case, the discount amount is $84 x 20% = $16. So the sale price is $84 - $16 = $68.