Can you help me to solve 5 questions please

1- Find the number of different terms of (x, + x2+ ...+X,.)". 2- i- How many five digit integers can we make chosen our digits from 5,8,8, 2, 6,6,0. ii- Find the number of integers in (i) which satisfies "if there is 8, then it is followed by 6" 3- Find The coefficient of x in (x*+x'+x"+x'+x*+x" ). 4- Find n such that o(n) =60. Page 2 of 7 5- Determine how many integer solutions to the equation X, +x,+X;+.x,+X, +X. =99 where X,+x, +x, =45, 29> X, , X2, X's 2-3, and X , , X. . X, 20