Answers

2014-09-27T23:24:18+08:00
84 liters
1/3 X - 7 = 1/4 X
note that X here is the value of water when it is full so when translated it will be...
1/3 full of water - 7 = 1/4 full of water

solving for x:
1/3X - 1/4X = 7
remember that we transposed the numbers, -7 and 1/4 X so they changed to 7 and -1/4 X
this will yield to
1/12 X = 7
multiply both sides by 12
X = 84

check:
1/3 (84) - 7 = 1/4(84)
28 - 7 = 21
21 = 21
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