How do you do this problem ?

Question

Substitute the given values into the formula and solve for the unknown variable.
P = 2L + 2W; P = 28, W = 8

14
20
10
6

Answer 1

P = 2L + 2W; P = 28, W = 8

First: find the length - substitute the numbers with the corresponding variables.

28 = 2L +2(8)
28 = 2L + 16

Sec: combine "like" terms - subtract 16 from both sides (when you move a term to the opposite side, always use the opposite sign).

28-16 = 2L + 16-16
28-16 = 2L
12 = 2L

Third: divide both sides by 2 to isolate the "L" variable.

(12)/2 = (2L)/2
(12)/2 = L
6 = L

Answer 2

P=2L+2W
=>28=2L+2*8
=>28-16=2L
2L=12
L=6

Answer 3

Since there are three variables (L, P & W) and you already know P=28 & W =8, the unknown variable is L. Therefore, we must find L, and we can only find L by getting L all by itself on one side of the "="...and getting a number on the other side. We do that by starting w/what we already know.

We know W=8, so 2W=16. (double both sides)

We now know 2W=16, so 2L+2W=2L+16. (add 2L to both sides)

Since P=2L+2W (see the question) and 2L+2W=2L+16 (see the last line), then P=2L+16. (If two things are both equal to something else, they're also equal *to each other*. This is called the transitive property.)

Since P=28 and P=2L+16 then 28=2L+16. (same reason as last line.)

Now we finally have an equation where L is the only variable left, which is necessary to get L by itself.

Since 28=2L+16, 12=2L. (subtract 16 from both sides, because we had to take away what as added.)

Since 12=2L, 6=L. (divide both sides in half, because we have to undo the "L"'s being multiplied by 2.)

Now we finally have the unknown variable by itself, since we undid everything that was done to "L". So the unknown value "L" = 6.

Answer 4

Hmmm, what exactly is it in this question that has you stumped?

P = 2L + 2 W
P = 28

So 28 = 2L + 2W

W = 8
So 28 = 2L + (2*8)
28 = 2L + 16
28-16 = 2L
12 = 2L
L = 12/2
So L = 6.

How do you do it? Exactly as it tells you - substitute the given values into the formula and solve for the unknown variable.

Answer 5

L= 6

Answer 6

when we substitute our given values, we get 28 = 2L + 2*8, 28-16 = 12 =2L. so L = 6
:)

Answer 7

L = 6

Answer 8

P = 2L + 2W
P = 28
W = 8

Isolate the variable you're solving for:

P = 2L + 2W
P - 2W = 2L + 2W - 2W
P - 2W = 2L
(P - 2W)/2 = 2L/2
(P - 2W)/2 = L

Substitute the known values (P = 28, W = 8) into the formula and solve. (left as an exercise for the asker)

Answer 9

Perimeter formula

P = 2L + 2W

28 = 2L + 2(8)

28 = 2L + 16

28 - 16 = 2L + 16 - 16

12 = 2L

12 / 2 = 2L / 2

12/2 = 2L/2

12/2 = L

6 = L

- - - - - - -s-

Answer 10

P = 2L + 2W

P = 28
W = 8

28 = 2L +2(8)
28 = 2L + 16
12 = 2L
L = 6