Answer
The equation is y=3x.
The table and the graph are present on the screenshot below.
Work Step by Step
The graph was created with cards on the y axis and hours on the x axis because you are making 3 cards per hour which means that on the graph you are rising up by 3 and moving over by 1 as it is cards per hour.
The equation is y=3x because at t=0 hours there are 0 cards which means the x and y intercept is (0,0) and the slope is 3 because you are making 3 cards every hour.