please help with our homework

Answer:
Perimeter formula for rectangle: 2L + 2B
Step-by-step explanation:
Length = 8.5 cm
Breadth = B
Perimeter = 24 cm.
2 (8.5) + 2B = 24
17 + 2B = 24
2B =24-17
2B = 7 cm
B = 7 / 2
B = 3.5 cm
Breadth = 3.5 cm
Length =8.5 cm
Perimeter =24 cm