Let's say...
The length= x
The width= y
Perimeter is 28 cm, so...
Equation 1
x+x+y+y=28
2x+2y=28
x+y=14
x=14-y
Length is 10 com longer than width, so...
Equation 2
x-y=10
Substitute Equation 1 into Equation 2
x-y=10
14-y-y=10
-2y=-4
y=2
Substitute y=2 into Equation 1
x=14-y
=14-2
=12
Answer: Length=12 cm, Width=2 cm
