Question

A body moving with velocity 30 metre per second after 10 seconds its velocity becomes 40 metre per second what was its average acceleration

Answer 1

$a = v - u \div t$

40-30/10
10/10
1
1m/s

Answer 2

use v = u+at

40 = 20+a*10 
a = 20/10 = 2m/sec^2