Question

The length of a rectangle is fixed at 11 cm. What widths will make the perimeter greater than 76 cm?

Answer 1

I'm not sure what grade/math level you are at.

Reasoning: There are two sides that are 11cm. You have 22 cm already. 76-22 will get you 54. What number adds up to 54? 25 adds up to 50, 26 adds up to 52, 27 adds up to 54. Anything higher than 27 will make it greater than 76cm.

Aglgebra:
11 + 11 + n + n = 76
2*11 + 2*n = 76
n = (77-22)/2
n = 27

Rectangle formula:
2*(width+length) = perimeter
2*(width+11) = 76
width+11 = 76/2
width = 76/2 - 11

Anything > 27cm will make the perimeter greater than 76cm.