Would anyone help With these questions it's the last one

Sanderson is having trouble with his assignment. his shown work is as follows: − 3 7 7 3 = − 3 7 × 7 3 = − 21 21 = −1 however, his answer does not match the answer that his teacher gives him. complete the description of sanderson's mistake. find the correct answer.

Aculinary club earns $1360 from a dinner service. they sold 45 adult meals and 80 student meals. an adult meal costs twice as much as a student meal. what is the cost of an adult meal?

Asalesperson set a goal to earn $2,500 in august. she receives a base salary of $1,000 per month as well as a 20% commission for all sales in that month. how many dollars of merchandise will she have to sell to meet her goal?