Question 1003134
The perimeter of a rectangle is 2(l+w)

 (3x+8) & (x+11)

Perimeter = 2((x+11)+(3x+8))

2(x+11+3x+8) = 70

2(4x+19)=70

/2
4x+19=35

4x= 35-19

4x= 16
x=4

(x+11) = 4+11=15

3x+8 => 3*4+8=> 20

Using Pythagoras theorem

Diag^2 = 15^2+20^2

= 225+400

= 625

diagonal = sqrt(625)

= 25

Diagonal = 25 units