Answer:
L=10cm , W=30cm
Step-by-step explanation:
First use the given that W=10+2*L
Use P=2W+2L=80, substitute W in the perimeter formula
2(10+2L)+2L=80 and solve for L,
20+4L+2L=80 isolate variable L and combine like terms,
6L=80-20,
L=10, so W=10+2*10=10+20=30
