A rectangle with an area of 124cm? has a length that is 4 times the width. What is the width? (Round your answer to the nearest tenth.)
A) 11.1 cm
B) 22.3 cm
C) 5.6 cm
D) 44.5 cm

c

Step-by-step explanation:

124=(4x)(x)

124=

31=

=x

5.6=x

Each room has width a, length b and heigth c. Let's use following formulas for area:
Floor and ceiling:
A1=a*b
Left and right wall:
A2=b*c
Front and back wall:
A3=a*c

a=30ft
b=20ft
c=9ft

We do not need to paint floor and ceiling, so total area that needs to be painted is:
A(unit)=2*A2+2*A3
A(unit)=2*b*c+2*a*c
A(unit)=2*20*9+2*30*9
A(unit)=360+540
A(unit)=900ft^2

We have 4 units so total area that needs to be painted is:
A(total)=4*A(unit)
A(total)=4*900
A(total)=3600ft^2