Let width = W. Then length L = 2W + 5.
[[model:questions/solutions/q6988.png]]
Perimeter = 2(L + W) = 70
• 2(2W + 5 + W) = 70
• 2(3W + 5) = 70
• 6W + 10 = 70
• 6W = 60 ⇒ W = 10
Length = 2(10) + 5 = 25 cm
Check: P = 2(25 + 10) = 2 x 35 = 70. ✓
Final Answer: 25 cm