If an object is moving linearly with constant acceleration to the east. In 15.0 seconds, the object accelerated from 0m/s to 85.0m/s. What is the acceleration of the object moving

For first condition,
t₁ = 0
v₁ = 0 m/s

For second condition,
t₂ = 15.0 s
v₂ = 85.0 m/s

For third condition, 5.00 seconds later,
t₃ = 15.0 + 15.00 = 10.0 second

a = $\frac{v_2 \, - \, v_1}{t_2 \, - \, t_1}$ = $\frac{85.0 \, - \, 0}{15.0 \, - \, 0}$ = 5.67 m/s²

v₃ = v₁ + a(t₃ - t₁) = 0 + 5.67(20.0 - 0) = 113 m/s