Answer:
B
Explanation:
The idea is to find if both car salesperson make the same amount of money at the end of the month. For making that we need to equal what one car salesperson makes in a month with what the other car salesperson makes.
The first made in one month $400 and for each car that he/she sold, there were $100 more.
The second made in one month $550 and for each car that he/she sold, there were $70 more.
So 400 + 100c = 550 + 70c
For which number of cars, c, do they make the same amount in one month
400 - 550 = c(70-100)
-150 = c(-30)
c = 150/ 30
c = 5
If both sold 5 cars per month, they will make the same amount in one month