Mrs. Safar purchases a bedroom set for $1600. Five percent sales tax is added to the purchase price and she must also pay a $60 delivery fee. If Mrs. Safar pays for the total cost of the bedroom set in 12 equal payments, how much is each payment? MAFS.7.EE.2.3

She would pay $145 monthly
1600+5%(80)+60=$1740:12=145

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.