@SqSehrish It's false.
The question is false.
The answer should be 6, but 6 is a digit, and not a number. The minimum number can be 10, x3 = 30 + 7 = 37 ?
Correct the question before excepting the correct answer.
@lady_stellz I prefer to do that in the tub, and prepare 3 plastic bin, clean water, water + cleaner, water + shine. But same process, I find it just more practical :)