#### Answer

Particle A
v = -10 m/s
Particle B
v = -20 m/s
Particle C
v = 95 m/s

#### Work Step by Step

Particle A:
The velocity will be equal to the slope of the position versus time graph;
$v = \frac{-60~m}{6~s}$
$v = -10~m/s$
Particle B:
We can read the velocity directly from the graph;
$v = -20~m/s$
Particle C:
The change of velocity will be equal to the area under the acceleration versus time graph;
$\Delta v = 85~m/s$
$v = v_0+\Delta v$
$v = 10~m/s + 85~m/s$
$v = 95~m/s$