Answer:
a) The perimeter of a rectangle is written as:
P = 2*L + 2*W
where L is the length amd W is the width (broad in this case).
here we have:
L = 8cm and W = b
then the perimeter is:
P = 2*8cm + 2*b
And we know that:
18cm ≤ P ≤ 50cm
where ≤ is used because there is written "not more" and "not less", so the equalities are allowed
now we can replace P by the above equation:
18cm ≤ 16cm + 2*b ≤ 50cm
now we can subtract 16cm in each side and get:
18cm - 16cm ≤ 2*b ≤ 50cm - 16cm
2cm ≤ 2*b ≤ 34cm
Now we can divide each side by 2.
1cm ≤ b ≤ 34cm/2 = 17cm
1cm ≤ b ≤ 17cm.
b) Here we have missing information, so this can not be answered.
(only knowing that one side length is x, and another side length is x + 3cm, we can know that x > 0cm, so the minimum value of x is really close to 0cm)
