Please show calculations 4. There are 25 coupons rolled up and placed inside round plastic balls in a box. There are 3 different types of coupons:

Please show calculations

4. There are 25 coupons rolled up and placed inside round plastic balls in a box. There are 3 different types of coupons: 10 of them can be redeemed for "free drinks", 10 can be redeemed for "free desserts", and 5 can be redeemed for "free entrees". If you shake the box and then randomly select one ball (with coupon), what's the probability that you will get a "free entrée" coupon ?    (a) 25% (b) 10% (c) 20% (d) 50% (e) None of these