PHYS question!!!!!!!!

1.A body is moving horizontally with uniform acceleration. the distance x of the body from the starting point is recorded by a camera flashing at regular intervals of 0.1s.the values of x recorded at successive flashes are 20cm ad 60cm.the acceleration of the body is?

我想問下我咁做岩唔岩?
the velocity of first 20cm(u)
=0.2/0.1
=2ms^-1
the velocity of the second part of 60cm(v)
=0.6/0.1
=6ms^-1
the acceleration of the body
=(v-u)/t
=(6-2)/0.2
=20m^-1