Question 380777
formula: P= 2L + 2W
"the perimeter of a photo is 72 cm."
2L + 2W = 72cm
"the length is twice the width"(note:if the sentence has is, is means equal sign)
L=2W
solution:
2L + 2W = 72
 L - 2W = 0  (cancel the same number and variable but diff. in sign)
------------
     3L = 72
      3 = 3
     ------
      L = 24

now for the width

2L + 2W = 72
2(24)+ 2W = 72
48 + 2W = 72
2W = 72 - 42 (transpose)
2W = 30
2  = 2
 W = 15

CHECKING:

2L + 2W = 72
2(24) + 2(15) = 72
48 + 30 = 72
     72 = 72 (CORRECT)