GMAT Problem Solving (PS) | Re: A certain store sells all maps at one price and all books at another

Let M = Number Of Maps
Let B = Number of Books

Based on the Question we can create below two Equations:

12M + 10B = 38 ------------- Eq.1
20M + 15B = 60 ------------- Eq.2

Multiply Eq. 1 By 5
Multiply Eq.2 By 3

60M + 50B = 190
60M + 45B = 180

Subtracting these two equations we get:

5B = 10

B = 2

Put this value of B in any of the equation, for the solution we will take Eq. No. 1

12M + 10B = 38 ------------- Eq.1

12M + 10*2 = 38

12M = 38 - 20

12M = 18

M = 18/12 = 3/2 = 1.5

We are
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