There are 60 Country CDs and 136 Rock CDs.
Rock and country CDs = 196
Country CD = x
Rock CD = x + 76
Country CD + Rock CD = 196
x + (x + 76) = 196
2x = 196 - 76
2x = 120
2x / 2 = 120 / 2
x = 60 * number of Country CD
Rock CD = x + 76 = 60 + 76 = 136
To check:
Country + Rock = 196
60 + 136 = 196
196 = 196
