I don't see a b or an m in this function, but generally, a linear function is of the form ax+b. The b in this equation (not sure if it is the same as your b), controls the shift of the function. Lower b by 3, the graph shifts down by 3.
So unless there is a minus sign before b, it has to be lowered by 3. (If there is a minus sign, it has to be increased by 3).
Answer: green = 25/100, red = 1/100
Step-by-step explanation: add ALL of the gumballs, there's your denominator, now you have 0/100 (1+74+25), count the amount of marbles you want to get the probability of, lets say green, there's your numerator (25) = 25/100
