Aprinting firm charged $35 for printing 600 sheets and $47 for printing 800 sheets find the formula assuming the relationship is linear

Here, Coordinates are: (35, 600) & (47, 800)
Now, Slope (m) = y2 - y1  /  x2 - x1
m = 800 - 600 / 47 - 35
m = 200 / 12 = 100 / 6
m = 50/3

Take any one coordinate into slope-intercept formula:
y - y1 = m(x - x1)
y - 600 = 50/3 (x - 35)
y - 600 = 50x/3 - 1750/3
y = 50x/3 + 50/3

In short, Your Answer would be: y = 50x/3 + 50/3

Hope this helps!