A because (0,-6) is the y-intercept so you start at the point you know. Then because slope is a rise over run fraction the slope can also be written as 2/1 which is rise 2 over 1.
Average acceleration: ( v - v o ) / Δ t v = 0 m/s, v o = 20 m/s, Δ t = 3.5 s a (average) = ( 0 m/s - 20 m/s )/3.5 s = - 20 m/s / 3.5 s = = - 5.7142857 m/s² ≈ - 5.71 m/s²
