Please Help me with this... This is MATLAB questions

Exercise 1 (30 points) Write a script to calculate the sum of a geometric series with N terms, (a). Write a script to calculate the particular of N- 75 and r-3/5. Use the Matlab build-in function 'sum' to perform the sum mation. (10 points, no for' or 'while' loops or simple geometric series summation formula allowed!) (b). Write a function with an appropriate user interface to enable customized input of both r and N. Display the calculated result with the Matlab build-in function 'disp(sprint0)' to format numbers into a string with a clear information (with both the input, r, N, and the specific output, SN). (20 points, a bonus will be given if the illegal input is checked and properly processed, e.g., invalid input parameter r when it is zero.)