Answer:
Let's use a system of equations to solve the problem:
x = number of cases of orange juice
y = number of cases of cranberry juice
From the problem, we know that:
x + y = 17 (Brett bought a total of 17 cases of juice)
15x + 8y = 192 (Brett paid a total of $192 for the juice)
We can solve for one of the variables in the first equation and substitute it into the second equation:
x + y = 17
x = 17 - y
15x + 8y = 192
15(17 - y) + 8y = 192
255 - 15y + 8y = 192
-7y = -63
y = 9
So Brett bought 9 cases of cranberry juice. We can substitute this value back into the first equation to find how many cases of orange juice he bought:
x + y = 17
x + 9 = 17
x = 8
Therefore, Brett bought 8 cases of orange juice.