Explanation:
Substitute the value x for any number, for example x=1, you substitute x for the value 1, so this is the final equation: y= -3(1)+5 and the answer you get is the value of y. Continue substituting x for any value in the graph of course and then write the answer for y which is the number you get by solving the equation. Then plot the graph with the points you got. Hope this helps, let me know if you need more help :)