I really am having trouble in these kind of problems that involve LRAM MRAM and RRAM

and i don't get this problem:

A particle starts at X = 0 and moves along the x-axis with velocity (t) = 5 for time [greater than or equal to] 0. where is the particle at t = 4?

there is an example in the book, but i get lost, i draw a graph, but i really don't know what to draw on the graph, is is x=4?