Answer:
160
Step-by-step explanation:
10 x 20=200
10 - 2 = 8
8 x 20 = 160
80 since he starts off with 38 stamps then gains 6 each month for 7 months (6x7=42) so 42+38=80
So hmm notice the picture below
that's the 30-60-90 rule, notice your triangle, the bottom-left-angle is a right angle, 90°, the angle atop is 30°, so the angle on the bottom-right has to be 60°, thus is a 30-60-90 triangle, and as you can see on the triangle on the left in the picture, those are the ratios for it
so 8 will be x, what is the longer leg or side in yours then? well, is
Youre gonna have to upload a picture of the porch, "figure below"