Ineed with number 6 someone work it out need to show work

If I read this diagram correctly then

DE   9x - 31 y    implies that the slope y / x = 9/31 = .29

and arctan .29 = 16 deg

and line CD  7x - 2y  implies that slope y / x = 7/2 = 3.5

and arctan 3.5 = 74 deg  

So in that interpretation the difference is 58 deg

But, I'm not certain of the terminology being used.