Which of the following expressions represents "5% of a number"?

To calculate the amount (A) that Sunny has in his savings account, he first finds the interest (I) earned and then adds it to the principal (P). Hence, A = P + I. Find another method to accomplish the same result.

Jill is shopping at a department store that is having a sale this week. The store has advertised 15% off certain off-season merchandise. Jill calculates the sale price by multiplying the regular price by 15% and then subtracting that amount from the regular price: SP = RP - 0.15(RP), where SP = Sale Price and RP = Regular Price. Find a simpler way for Jill to calculate the sale price as she shops.