Use the slope formula to find the slope of the line through the two points
m = (y2 - y1)/(x2 - x1)
m = (7 - 1)/(1 - (-2))
m = (7 - 1)/(1 + 2)
m = 6/3
m = 2
Then use one of the points. So let's say (x1,y1) = (-2,1)
So we'll plug this into the point slope form below
y-y1 = m(x-x1)
y-1 = 2(x-(-2))
y-1 = 2(x+2) <<<--- this is one of the possible answers
If we use the point (x1,y1) = (1,7) instead, then we'll have
y-y1 = m(x-x1)
y-7 = 2(x-1) <<<--- this is the other possible answer
Both equations represent the same line.