The length of a rectangle is fixed at 15cm. What widths will make the perimeter greater than 100cm?

30 + 2W > 100
2W > 70
W > 35

The width must be greater than 35 cm

Finding width (x):
2(15 + x) >= 100
15 + x >= 50
x >= 35

Answer: greater than 35 cm

Proof:
2(15 + 35) = 100
2(50) = 100
100 = 100

100cm - 15cm - 15cm = 70cm.
70cm divided by 2 = 35cm.
this is the width that will make the perimeter of the rectangle exactly 100cm.
so to make the perimeter larger without interferring with the length, the width of the rectangle must be greater by 35cm.

perimeter of a rectangle is 2(l+b)
=2l+2b
=2 x 15 + 2b
therefore,
100=30+2b
2b=70
b=35

but b cannot be greater than lt.

hence the perimeter of this rect. cannot exceed 100cm

30+2W>100
2W>70
W>35

2(15 + w) > 100
30 + 2w > 100
2w > 100 - 30
2w > 70
w > 70/2
w > 35

∴ the width must be greater than 35 cm.

Answer : The width must be greater than 35 cm.

Proof:

Perimeter of rectangle 2(l+w). Since l = 15 cm and is fixed

we get 2(15+w) = 30 + 2w this should be greater than 100 cm.

so, 30+2w > 100 or 2w > 100-30 or 2 W > 70 or w > 35

15 + 15 + 2W > 100
30 + 2W > 100
2W > 70
W > 35

The length is actually the width, since the other side has to be greater than 35 cm.

2L + 2W >100
2(15) + 2W >100
30 + 2W >100
2W > 70
W > 35