Planks cost $3 each and plywood sheets cost $5 each. nick purchased 9 planks and 2 sheets of plywood. how much money did nick spend all together? explain how you solved the problem.

So if nick purchased 9 planks and they cost 3$ each then you could add 3 nine times or multiply 3x9 which is 27$
now the same with the plywood but i would be 10$ he spent on those
now add 27 to 10 and you get 37$ 
so he spent 37$ all together

Period is the time it takes for one “cycle” to complete. in the parent sine function, period is 2*pi since sin(0) = 0, sin(pi/2) = 1, sin(pi) = 0, sin(3pi/2) = -1, and sin(2pi) = 0. at that point, the sequence repeats itself. i’m not sure if your graph is similar to the sine function since you didn’t provide a picture, but you can find the period by looking at a graph.