Answer: 
Step-by-step explanation:
The area of a rectangle can be calculated with the formula:
l: the length of the rectangle.
w: the width of the rectangle.
The area of the remaning wall after the mural has been painted, will be the difference of the area of the wall and the area of the mural.
Knowing that the dimensions of the wall are 
by 
, its area is:
As they are planning that the dimensions of the mural be 
by 
, its area is:
Then the area of the remaining wall after the mural has been painted is:
Answer:
B. 40
C. 8
Step-by-step explanation:
Answer: 120 beats per 45 seconds
Step-by-step explanation:
This is a units conversion problem: you have time and you want to convert that to money. Any units conversion problem involves multiplication by 1 in various forms. When you are given 7.5 min = 1 bottle = 500g, you know that (500 g)/(7.5 min) = 1 because the numerator and denominator are equal. (Of course, you are aware that 500 g = 0.500 kg.) The idea is to choose the forms of 1 that cause units you don't want to cancel, leaving only the units you do want.
The glass for recycling that would save enough energy to power an oven for 6 hours costs 120p.
