Question

an object Travels 16 m in 4 seconds and then another 16 m in 2 seconds what is the average speed

Answer 1

Here 
Total distance = 16 m + 16 m = 32 m
Total time = 4 s + 2 s = 6 s

Average speed = total distance/total time
                           = 32/6
                           = 5.33 m/s

Answer 2

D=S×T then S=D÷t
then
D=16m t=4s. S= D ÷ t

$s = 16 \div 4 = 4$
s= d÷t
then
$s = 16 \div 2 = 8$
AVERAGE
4+8=12
$12 \div 2 = 6$
therefore
average speed is 6m/s