Answer
Each of the other 4 partners owns $\frac{3}{20}$ of the business.
Work Step by Step
The other partners own $\frac{3}{5}$ of the business, so each owns
$\frac{3}{5} \div 4$
Estimate
$1 \div 4 = \frac{1}{4}$
Solve
$\frac{3}{5} \div 4$ = $\frac{3}{5} \times \frac{1}{4}$ = $\frac{3}{20}$
Check
$\frac{3}{20} \times 4$ \times= $\frac{12}{20}$ = $\frac{3}{5}$