Answer:
b) $14
Step-by-step explanation:
Let x be the cost of each CD and y be the cost of each DVD,
Since, 3 CDs and 5 DVDs cost $ 137,
⇒ 3x + 5y = 137 -------(1),
Also, 2 CDS and 7 DVDs cost $ 161,
⇒ 2x + 7y = 161 --------(2),
7 × equation (1) - 5 × equation (2) ( ∵ we need the value of x so we have to eliminate y for this LCM(7,5) = 35 )
We get,
21x - 10x = 959 - 805
11x = 154
⇒ x = = 14
Hence, the cost of each CD is $ 14,
Option 'b' is correct.