David borrowed a total of $3000 from two student loans. One loan charged 5% simple interest and the other charged 4.5% simple interest, both payable after graduation. If the interest he owed after 5 years was $687.50, determine the amount of principal for each loan.

Tabby sells clothing at a retail store, and she earns a commission of 6.25% on all items she sells. last week she sold a pair of jeans for $32.50, a skirt for $18.95, and 2 blouses for $14.95 each. what was tabby's total commission? a $4.15 b $5.08 c $81.35 d $348.60

If you could answer these your a life saver

Math i have no idea how to do a and b