Question

as a salesperson at trading cards unlimited, justin receives a monthly base pay plus commission on all that his sells. if his sells$500 worth of merchandise in one month, his is paid $410. if his sells $900 of merchandise in one month, his is paid $498. Find justins salary when his sells $3,400 worth of merchandise.

Answer 1

Total = base pay + commission

commission = rate * sales (where rate is the % of sales that Justin gets)

At $500:
total = base pay + commission on $500
410 = base pay + (rate * 500)

At $900:
total = base pay + commission on $900
498 = base pay + (rate * 900)

We can rewrite the first one as
base pay = 410 - (rate * 500)
and the second as
base pay = 498 - (rate * 900)

And since his base pay is always the same, that means
410 - (rate * 500) = 498 - (rate * 900)
So
(rate * 900) - (rate - 500) = 88
rate * (900 - 500) = 88
rate * 400 = 88
rate = 88 / 400
rate = 0.22, or 22%

And we know:
410 = base pay + (rate * 500)
so
410 = base pay + (0.22 * 500)
410 = base pay + 110
300 = base pay

Now we have our formula in general terms:
total = base pay + (rate * sales)
total = 300 + (0.22 * sales)

So when sales = $3,400:
total = 300 + (0.22 * 3400)
total = 300 + 748
total = $1,048

Done!

Answer 2

Tank you !!