In 1 pint, there are 16 ounces. Thus, 64 pints can be converted to ounces as follows:
[tex]\begin{gathered} 64\text{ pints}=\frac{64\text{ pints}}{1}\cdot\frac{16\text{ ounces}}{1\text{ pint}}=1024\text{ ounces} \\ \end{gathered}[/tex]
This means that the bushel is equivalent to 1024 ounces.
Since there are 16 jars in 1 crate, we have the following:
[tex]\begin{gathered} \\ 16\text{ jars}\cdot20\text{ ounces}=320\text{ ounces} \end{gathered}[/tex]
Divide the number of ounces in 5 bushels by the number of ounces in a crate.
[tex]\frac{5(1024\text{ ounces)}}{320\text{ ounces}}=\frac{5120\text{ ounces}}{320\text{ ounces}}=16[/tex]
Therefore, the farmer must have 16 crates.