1. natalie bought 5 cartons of milk and received $2.50 in change. the following week she bought two cartons and received $7 in change. if she gave the same amount of money to the shopkeeper each time, work out the cost of each carton of milk.
2. yvonne wants to buy a car which costs $23,000. she pays a deposit of $14,000 and then arranges to pay an amount each month for the next three years. how much should each monthly payment be if she wishes to payoff the car in three years?
3. at the end of the term each student in the class was given their average test score in maths. during the term the class had sat three tests. for two of her tests leonie had obtained results of 93% and 85% but she had forgotten her result in the third. work out this unknown result for leonie if she scored an average of 91%