Logic problem, proposed by Euler A professor of mine asked me this challenge.
"(Proposed by Euler) A person bought horses and oxen. Paid 31 shields per horse and 20 per ox, and found that all oxen cost 7 shields more than all the horses. How many horses and oxen were bought? "
And I is not getting ...
Called C the amount of horses and cattle amount of B ...
From the data we have $31C=x$ and $20B=x+7$, soon $$31C=20B-7\Rightarrow20B-31C=7$$ Now just solve the Diophantine equation, am I correct?

Yes, that's right.
Note that this linear Diophantine equation has infinitely many solutions... I suppose the "most likely" solution is the one with positive number of horses and oxen that costs the least total.
