Explanation:
1.) Firstly, you need to count out how many things there are. 4 app, 5 entrees, 2 desserts. This makes 11 different things
2.) for 11 numbers there can be 9 ways for each number for 1st nine places since 0 can't be the fist figure and next two are reciprocated from 10 numbers. Therefore 10!/2!
3.)So 99 combinations have 10!/2! Permutations hence total ways are 99*10!/2!