help me with this problem i can find the distace.?

Question

the problem is to find how far it went in first 3 sec but i don't know how to find the answer i know it acerate from 0-1 sec and 1-3 it it has sonsant speed of 10m/s

speed (m/s)
|
|
| _ _
|/_______
TIME (s)

Answer 1

In the first second:
v = at
10 = a*1
a = 10
s = s0 +v0t + (1/2)at^2
s = 0 + 0 + (1/2)(10)(1^2)
s = 5 m, which becomes s0 for the next part:
s = s0 +v0t + (1/2)at^2
s = 5 + 10*2 + 0
s = 25 m