SOLUTION: A book seller buys 120 volumes of a certain books.He sells some for 18p each and disposes of the remainder during a sale at 12p each.If the total receipts are £ 19.20.how many vo

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Question 1137567: A book seller buys 120 volumes of a certain books.He sells some for 18p each and disposes of the remainder during a sale at 12p each.If the total receipts are £
19.20.how many volumes were sold at each price
Found 2 solutions by ikleyn, Theo:
Answer by ikleyn(52781)   (Show Source): You can put this solution on YOUR website!
.
Let x = # of the 18 p volumes, y = # of 12 p volumes.


From the condition, you have these 2 equations


         x +      y = 120       (1)    (counting volumes)

      18*x +   12*y = 1920      (2)   (counting money, in " p ")


From equation (1), express  y = 120 - x  and substitute it into equation (2), You will get


    18x + 12*(120-x) = 1920.


Express x and calculate answer


    x =  = 80.


Then from equation (1),  y = 120 - 80 = 40.


ANSWER.  80 volumes at 18p and 40 volumes at 12p.


CHECK.   80*18 + 40*12 = 1920 p.   ! Correct !

The problem solved using 2-equation setup and the Substitution method.


Answer by Theo(13342)   (Show Source): You can put this solution on YOUR website!
i believe 100 pence to the pound.

x = number of books sold at 18 pence each.

y = number of books sold at 12 pence each.

total books sold is 120, therefore x + y = 120.

since 100 pence to the pound, then 19.20 pounds is equal to 1920 pence.

total receipts were 1920 pence, therefore 18x + 12y = 1920

you have 2 equations that need to be solved simultaneously.

they are:

x + y = 120
18x + 12y = 1920

in the first equation, solve for y to get y = 120 - x.

in the second equation, replace y with 120 - x to get 18x + 12 * (120 - x) = 1920.

simplify to get 18x + 1440 - 12x = 1920.

combine like terms and subtract 1440 from both sides of the equation to get 6x = 1920 - 1440

combine like terms to get 6x = 480.

solve for x to get x = 80.

since x = 80, then y = 140 - x = 40.

total receipts are (18 * 80) + (12 * 40) = (800 + 640) + (400 + 80) = 1440 + 580 = 1920.

total receipts for books at 18 pence each is 1440 pence = 14.40 pounds.

total receipts for books at 12 pence each is 580 pence = 5.80 pounds.

total receipts is 1920 pence = 19.20 pounds.

your solution is that 80 books were sold at 18 pence each and 40 books were sold at 12 pence each.












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