Question

write a linear equation of (2,5), (4,10), (6,15), (8,20)

Answer 1

Compute the slope: m = (10−5)/(4−2) = 5/2. All pairs give the same slope, so the line is y = (5/2)x + b.
Use (2,5): 5 = (5/2)(2) + b → 5 = 5 + b → b = 0.

So the linear equation is y = (5/2)x (or y = 2.5x).