HOw do I find the range of a funtion

How to do a maths question? i have a mock

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?

Andres wants to share 1/2 of his birthday cake with his friends. if he has 8 friends, how much of the cake will each friend recieve? draw a model to support your work (its ok if you cant)