The mistake is that they subtracted 21 instead of adding it. you would have had to added 21 to the left side to cancel it out and added 21 to the right side to get p= 55
Answer:
one person one number
Step-by-step explanation:
Area of building is
.
<u>Step-by-step explanation:</u>
Here we have , a figure in given below picture where we have to find volume of this office building , Let's find out:
If we look closely we see that it's basically cuboid with dimensions 50 m by 110 m by 70 m . But there's one small cuboid sliced off from this cuboid with dimensions 50 m by 10 m by (110-90) m i.e. 50 m by 10 m by 20 m .
Area of building = Area of larger cuboid - Area of smaller cuboid
Area of cuboid = 
⇒ Area of building = Area of larger cuboid - Area of smaller cuboid
⇒ 
⇒ 
⇒ 
Therefore, Area of building is
.
2x (Multiplied by) 6
You cannot combine 2x and 6 because x is an unknown variable that is attached to a coefficient. Hope this helps!