Are those functions? It said to determine if each relation is a function but I forgot how to find functions. Can someone please help me and tell me how you know??

The graph shows the distance y, in inches, a pendulum moves to the right (positive displacement) and to the left (negative displacement), for a given number of seconds x. how many seconds are required for the pendulum to move from its resting position and return? enter your answer in the box.

Solve the equation - 2(m -30) = -6m a-15 b-13 c-8 d8

Richard save $32 in march he saved $48 in april and $38 in may then richard spent $113 on a keyboard how much money does richard have left