240 ft^2 = L X W
240 = 3W x W
240 = 3W^2
W = 8.94427 ft
L = 3W = 3(8.94427)
L = 26.8328 FT
Answer:

Step-by-step explanation:
The given equation is 
Group similar terms to get:


Square both sides to obtain:


Add 6 to both sides

Simplify the right hand side to obtain;

The mode is the number repeated most often, so if we arrange these numbers in order, we can see what numbers repeat the most-
1 1 1 2 3 3 5 7 8 8 9
The number that repeats the most is 1
(1 counted 3 times)
(3 counted twice)
(8 counted twice)
This one is very simple.
create a simple equation to find out
15 = 12 + x
subtract 12 from each side
x= 3
the missing number is 3
or, to be even simpler, take the total, subtract the total from the number you know and the difference is the missing number.
hope I helped
ALSO, we can check going down vertically. 3 + 10 =13. this is the total listed at the bottom.