Problema Solution
A store is selling bundles of recordable compact discs (CD-R) and rewriteable compact discs (CD-RW). Each Bundle contains the same number of discs. The store has advertised 15 CD-Rs for $1 and 10 CD-RWs for $1. Doug has exactly enough money to buy 6 bundles of CD-RWs and 1 bundle of CD-Rs. Buying 7 bundles of CD-RWs would have left him $2 short of the amount due. How many discs are in each bundle?
Answer provided by our tutors
let x = the number of discs in each bundle
since 15 CD-Rs for $1 follows that 1 CD-R is 1/15
since 10 CD-RWs for $1 follows that 1 CD-RW is 1/10
the cost of 1 bundle of x CD-Rs is x(1/15)
the cost of 1 bundle of x CD-RWs is x(1/10)
Doug has exactly enough money to buy 6 bundles of CD-RWs and 1 bundle of CD-Rs. Buying 7 bundles of CD-RWs would have left him $2 short of the amount due.
6x(1/10) + x(1/15) = 7x(1/10) - 2
by solving the equations we find
x = 60 discs
click here to see the step by step solution of the equation
each bundle has 60 discs.