Furnace repairs

Question

A repairman purchased several furnace -blower motors for a total cost of $210. If is cost per motor had been $5 less, he could have purchased one additional motor. How many motors did he buy at the regular rate?

Please help

Answer 1

regular rate = r
discount rate = (r-5)
number bought = n
number that would have been bought = (n+1)
so
210 = r n
and
210 = (r-5)(n+1) = r n + r - 5 n -5
from the first equation r = 210/n
then the second
215 = (210/n)n +210/n -5 n
5 = 210/n -5 n
5 n = 210 -5 n^2
n^2 + n - 42 = 0
(n-8)(n+7)=0
n = 8

Answer 2

sorry
(n+7)(n-6) = 0
n = 6

Answer 3

check
r = 210/n = 35
r-5 = 30
n+1 = 7
30 * 7 = 210 check

Answer 4

thank you very much

Answer 5

HELP!!!!!I need a better explination.