Question

Abc bookstore sells new books, n, for $12, used books, u, for $8, and magazines, m, for $5 each. The store earned $340 revenue last month. The store sold 5 more used books than new books, and twice as many magazines as new books. Using substitution method, how many magazines, new books, and old books did ABC bookstore sell?

Answer 1

14

Explanation:

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Answer 2

The number of new books sold = 10

The number of used books sold (u) = 15

The number of magazines sold (m) = 20

Explanation:

Let us assume the number of new books = n

So, the number of used books sold (u) = New books sold + 5 = n + 5

Also, the number of magazines sold (m) = 2 x ( Number of new books sold)

= 2 n

⇒ u = n + 5, m = 2 n

Here, the cost of each new book n- = $12

So, the cost of n new books = n x ($12) = 12 n

the cost of each used book u = $8

So, the cost of u = (n+ 5) used books = n+5 x ($8) = 8 n + 40

the cost of each magazine m = $5

So, the cost of m = (2n ) magazines = 2n x ($5) = 10 n

Also, total earnings = $340

⇒ 12 n + 8n +40 + 10 n = 340

or, 30 n = 300

or,n = 300/30 = 10

Hence the number of new books sold = n = 10

The number of used books sold (u) = n + 5 = 15

The number of magazines sold = m = 2 n = 20