Using R, Please write a user define function bill_fct to calculate the bills for clients based on the Golden Corral Cos policy. Followings are the prices based on the Golden Corral Cos client age and bill policy :

Lunch

Age 4-8 $5.99

Age 9 59 $8.69

Senior 60- up $8.19 $8.69

Note: (1) You need use multi-if-else control construct to calculate clients lunch bill based on clients age. The age and discount coupon arguments are required when calling function bill_fct. If there is no coupon, the coupon value should be zero