Please help me ASAP thank you

What are linear equations? could'ya explain too me, ? ! and how do you see what graph is a proportional relationship?

Atreasure chest sinks at a rate no less than 20 feet er second. the floor of the icean is at most at -4,200 feet. will the tresure chest reach the ocean floor in less than 3 minutes? explain.

Function 2 f(x) = -x2 + 2x - 15 function _has the larger maximum. (put 1 or 2 in the blank space) numerical answers expected! answer for blank 1: