number of pencils sold --- x
number of notebooks sold = 3x/7
cost of a pencil --- y
cost of a notebook = y+4
(3x/7)(y+4) - xy = 120
times 7
3x(y+4) - 7xy = 840 ----> 3x(y+4) = 7xy + 840
xy + (3x/7)(y+4) = 750
times 7
7xy + 3x(y+4) = 5250 -----> 3x(y+4) = 5250 - 7xy
7xy + 840 = 5250 - 7xy
xy = 315 , sub that into
3x(y+4) = 7xy + 840
3xy + 12x = 7xy + 840
945 + 12x = 2205 + 840
x = 175
the y = 315/175 = 9/5 = 1.80
so number of pencils = 175
number of notebooks = 3x/7 = 75
cost of a pencil = 1.80
cost of a notebook = y+4 = 5.80
State your conclusions
There were 3/7 as many notebooks as pencils being sold. Each notebook
cost $4 more than each pencil. The total amount received from the sale of
notebookswas $120 more the amount received from the sale of pencils.
The total amount received was $750.
(a) What was the total amount received from the sale of pencils?
(b) How many notebook and pencils were sold altogether?
(c) What was the cost of each notebook?
1 answer
1 answer