Solve Kinematics: Find Velocity & Displacement of Speedboat

[iaberrant]

Homework Statement

A speedboat starts from rest and accelerates at +2.03 m/s2 for 8.87 s. At the end of this time, the boat continues for an additional 8.86 s with an acceleration of +0.380 m/s2. Following this, the boat accelerates at -1.20 m/s2 for 8.11 s. (a) What is the velocity of the boat at t = 25.84 s? (b) Find the total displacement of the boat.

Homework Equations

The equations to be used are :
v= u + at
s= ut + 1/2 at^2

The Attempt at a Solution

i understand that you use the above equations to work through each stage in the speedboats journey:
stage 1: v=11.69m/s
s=40.23m
stage 2: using the previous velocity
v=16.47m/s
s=102.236 m
stage 3: using the previous velocity
v= 7.28
s= 100.11

so the solution is velocity at 25.84 seconds is 7.28 m/s that part of my working is correct, what i don't understand is how to find the total displacement, please help

 

[method_man]

Draw a v-t diagram and calculate a surface under the lines.