Joel and sara want to know the combined amount of money they made last week. they both made $9.75 per hour, but joel also made an $18 bonus. joel says the combined amount is 9.75j + 18 + 9.75s, where j is the number of hours he worked, and s is the number of hours sara worked. sara says the combined amount is 9.75(j + s)+ 18. who is correct? explain.