Can someone helm me with this problem plz and show work

I'm so close to finishing all these.

What are the measures of ∠a, ∠b, ∠c and ∠d? explain how to find each of the angle measure.

1c) the number 131 is a term in the sequence defined by the explicit rule f(n)=5n-4. which term in the sequence is 131? 2a) write the first four terms of the function f(n)=n^2-1 2b) what is the 10th term of the sequence defined by the explicit rule f(n)=n^2-1 2c) the number 224 is a term in the sequence defined by the explicit rule f(n)=n^2-1. which term in the sequence is 224?