My first step is always to draw a picture
We are told the length is 4 less than twice the width
l = 2w-4
We are told the perimeter is 34
P =2(l+w)
Substitute the first equation in for l
P = 2( 2w-4 + w)
Combine like terms
34 = 2( 3w-4)
Distribute the 2
34 = 6w -8
Add 8 to each side
34+8 = 6w-8+8
42 = 6w
Divide by 6
42/6 = 6w/6
7 =w
Now we can find l
l = 2w-4 = 2(7) -4 = 14-4 = 10
The question asks for the area
A = l*w = 10 *7 = 70