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?

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