leandra has 40 coins that total $7.15. all of her coins are dimes, d, and quarters, q. which system of equations models this situation?

Answer 1

d + q = 40

10d + 25q =715

multiply 1st equation by 10, then subtract result from 2nd equation to eliminate one variable, leaving

(25-10)q = 715-400

15q = 315, divide both sides by 15

q = 315/15 = 21 quarters

d= 40-21 = 19 dimes

10(19) + 25(21) = 190 + 525 = 715