Use the formula for acceleration:
a = Δv ÷ Δt
This is the same as:
a = ( v₂-v₁ ) ÷ Δt
Substitute values into equation and solve.
a = (230 m/s [E] - 245 m/s [E] ) ÷ 7 s
a = -15 m/s [E] ÷ 7 s
a = -2.1428 m/s² [E]
Therefore the acceleration of the plane is -2 m/s² [E].