I'm guessing that any "0's with slanted lines through them" would be the greek letter theta, which looks like this: \theta.
Beyond that, I really cannot help you unless you show some work and show where you got stuck.
I'm sure that your pre calc book contains all the necesary trig...
In your problem statement:
P(r_1 )=0.55 and P(g_2 |g_1 )=0.75
but I don't know how you got your answer because .55*.75 = .4125, though I do agree that .33 is very close to the answer, depending on how you round the decimal.