Question 1202508
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Fifteen decreased by the quotient of a number and 3 is 20.
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Just some limited help:
"The quotient of a number and 3"
{{{x/3}}}



"Fifteen decreased by the quotient of a number and 3"
{{{15-x/3}}}



You should understand all of that clearly enough, and should be able to do the next part on your own.