we call W the width and L the length of the rectangle. So it is 34=2(L+W) (1) end L=2W+5 (2)
we plug the value of L from the(2) to (1) and we have. 34=2(2W+5+W) ---->>>> 34=2(3W+5) --->>>
34=2(3W+5) ---->>> 34=6W+10 --->>> 24=6W and W = 4 cm so from (2) we get L=2*4+5 = 13 cm
check the perimeter is 2(4+13) = 2*17 = 34 cm