So you have:

1) Start off by multiplying both sides by x to simplify the problem:

2) Now isolate the x by moving all terms with x onto one side and all other terms onto the other side:

3) Finally, divide by 3 on both sides to find the value of x:

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Answer: x =
A. is obviously the most easiest one, as you just have to fill it up 3 times to get 3 gallons.
The next one to measure exactly 3 gallons of water is B), because:
1) the 100-gallon barrel is more than 1 gallon, and is much more harder than 3 gallons.
2) Each person's 'palm' can hold different amounts of water, and so it can vary by the size of the palm.
So IF it cannot be (A), then your next choice is (B), as you only need 768 teaspoons for each gallon.
But, you should report this problem to the teacher, since A is obviously the best choice
Answer:
100 im pretty sure because 10 x 10 = 100