Finding the mean is you have to add it all up:
49+55+52+46+47+42+38= 328
The divide it by the amount of numbers so, 329/7= 47.
Subtract 47 from every number then, but even if you get a negative number you gotta keep it a positive so just ignore it if you get a negative answer when subtracting, once you do that you would add up those answers you got so;
2+8+5+1+0+5+9= 30
Then divide it again, 30/7
Which then you get the M.A.D which is 4.3, rounded to the nearest ten.
It must be 6 since the length sides r doubled and it's similar
The answer is 28
Hope this helped!!
