Question

A salesperson earns $450.20 per week plus 15% of her weekly sales. Which of the following describes the sales necessary for the salesperson to earn at least $600.10 in one week?

Answer 1

First we must construct an equation to model the problem. (In this case we will use an inequality instead) This is what I came up with:
         450.20+0.15s>=600.10

This equation shows how if her base earnings ($450.20) are added to 15% of her sales, represented by s, then the total will be greater than or equal to $600.10
Next, we simply solve for s. (steps shown below)

1) 450.20+0.15s>=600.10 (simply restating the inequality)
2) 0.15s>=149.90 (here I isolated the variable)
3)0.15s/0.15>=149.90/0.15 (Finally I solve for s by dividing both sides by 0.15, this will isolate s on the left and leave the answer on the right)
4) s>=999.33... (here I found the total sales the salesperson would need to reach his/her goal of earning a minimum of $600.10; the 3's after the decimal are repeating so in the next step I will round up to the nearest hundredth (b/c this is what money is rounded to and if I round down he/she would make less than her goal. This means i must round up.))
5) s>=999.34 (simple rounding; once again I rounded up b/c rounding down would slightly bring the total earnings to less than the goal)

Therefore, the salesperson would need his/her sales to be $999.34 in order for his/her total earnings for the week to be at least $600.10 (greater than or equal to $600.10)

Hope this helped!