$14$ tins contains $210$ liters of oil. How much oil is contained in $1$ tin?

By unitary method, we have:
Cost of $14$ tins $=210$liters
Cost of $1$tin $=\left(\frac{210}{14}\right)=15$liters $\left[Lesstins,lessliters\right]$

Hence, the oil in $1$tin is $15$liters