I don’t know helppp!!

Write a corresponding real world problem to represent 2x - 125=400

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?

Suppose y varies directly with x. write a direct variation equation that relates x and y. then find the value of y when x=12 y=7 when x=3