If the perimeters are equal, you can form an equation to find x:
x + x + 12 + x + x + 12 = x + 11 + x + 11 + x + 16
4x + 24 = 3x + 38
- 3x
x + 24 = 38
- 24
x = 14
Now you can substitute the x value into the perimeter:
(4 × 14) + 24
56 + 24 = 80 cm
(3 × 14) + 38
42 + 38 = 80 cm
So the perimeter would be 80 cm.
I hope this helps!
Step-by-step explanation:

Answer:
3^3 and 36^1
Step-by-step explanation:
3x3x3x3 is multiplying that 4 times so it is to the power of 4
36 is just once so it is to the power of one
Let x=annual interest rate of 18000 investment.
Then
18000*x - 9000(x-0.006)=648
Solve for x
18000x-9000x+9000*0.006=648
9000x=648-54=594
x=594/9000=0.066
Answer:
the annual interest rate of the 18000 investment is 6.6%
the annual interest rate of the 9000 investment is 6.0%