Start by stating the given info as mathematical expressions:
1. "<span>The width of a rectangle is 6 cm less than its length."
2. "I</span><span>ts perimeter is 80 cm."
Using the formula for perimeter (
) we can show:
.
We now have 2 equations in 2 unknowns and can solve by substitution:
</span>
The length is 23cm.
Having the length w can then find the width:
The width is 17cm.
And finally the area:
The area is
.
As a check we can use the known perimeter:
Checks true.
1. "<span>The width of a rectangle is 6 cm less than its length."
2. "I</span><span>ts perimeter is 80 cm."
Using the formula for perimeter (
We now have 2 equations in 2 unknowns and can solve by substitution:
</span>
The length is 23cm.
Having the length w can then find the width:
The width is 17cm.
And finally the area:
The area is
As a check we can use the known perimeter: