What's the value of y is point a is (2,1) and point b is (8,y) and the slope is 5/2

With alll of except for the 2 that i did already

Which of the following equations are equivalent to -2m - 5m - 8 = 3 + (-7) + m? -15m = -4m -7m - 8 = m - 4 -3m - 8 = 4 - m m - 4 = -7m - 8 -8 - 7m = -4 + m -8 - 3m = 4 - m

An octagonal prism has jow many lateral faces?