For the data set 62, 73, 74, 75, 76 the mean is 72 what is the mean absolute deviation

How to do this , and can some one explain

Acompany that manufactures and sells guitars made changes in their product range. from the start they had 20 models. then they reduced the number of models to 15. as a result, the company enjoyed a 10% increase in turnover. - how much did the stock level change? in (%)

What is the measure of ac? 5 units 13 units 26 units 39 units 3x- 2b 6x + 9