.
Let me re-write your problem in proper English-Math language.
A tank is 2/3 full. After
draining off 120 liters, it's just 1/4 full.
What is the
capacity of the tank.
SOLUTION
Let x be the capacity of the tank, in liters.
Then from the condition of the problem
- 120 =
.
It is your basic equation.
To solve it, multiply both sides by 12. You will get
8x - 120*12 = 3x
8x - 3x = 120*12
5x = 1440
x =
= 288.
ANSWER. The capacity of the tank is 288 liters.
Solved.
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Notice how accurately I use English words, punctuation signs and capital letters, when I start new sentence (!)