Answer:
w=8; l=26 ft.
Step-by-step explanation:
1. according to the condition the phrase 'the length is 10 longer than 2 the width' means length=2*width+10;
2. according to the condition the perimeter is p=68;
3. the formula of the perimeter of the given rectangle is p=2(length+width);
4. after substitution into the formula (3) expression for the length (1):
perimeter=2(2*width+10+width); ⇔ perimeter=2*(3*width+10);
5. if to substitute perimeter=68, then 2*(3width+10)=68; ⇒ width=8 ft.
6. according to the (1) the length is 2*8+10=26 ft.