Can anyone help me?

Sorry, Anonymous.....but Q can't possibly be "26"

This would imply that :

26 + l 16.4 l  = 9.6      which definitely isn't true......adding an absolute value to 26 has to result, at the very least, in a value of 26....and this cannot equal 9.6  !!!!!

Q + |16.4| = 9.6     notice that the absolute value of a positive number is just the number itself.....so we have

Q + 16.4 = 9.6    subtract 16.4 from both sides

Q =  - 6.8

16.4 can be +ve or -ve

if +ve

Q+16.4= 9.6

Q= 9.6-16.4

Q= -6.8

if -ve

Q-16.4= 9.6

Q= 9.6+ 16.4

Q= 26

So the solution set is Q = {26, -6.8}