Answer:
length=11 width=10
Step-by-step explanation:
Create two equations with length(l) and breath(w) as our unknowns
2l+2w=42
2l=42-2w
2l/2=(42-2w)/2
l=21-w(equation 1)
lxw=110
lw=110
Substitute equation one into equation two
(21-w)w=110
21w-w²=110
Write your equations in standard quadratic form
0=w²-21w+110
solve this as a quadriatic tri nominal
0=(w-10)(w-11)
0=w-10. or 0=w-11
10=W. 11=L