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.

to find the perimeter of the rectangle this is the expression:

x-9+x-9+3x-4+3x-4=138

if we simplify it:

8x-26=138

remember, 138 is what it all adds up to

the length is 11.5cm

the width is 57.5cm

the area is 661.25cm^2

the answers might not be correct use at own risk