1. **State the problem:** We are given that pumpkins cost 5 each and tomatoes cost 3 each. The total sales amount to 98. We know 10 pumpkins were sold, and we need to find the number of tomatoes sold. 2. **Define variables:** Let $x = 10$ be the number of pumpkins sold. Let $y$ be the number of tomatoes sold. 3. **Write the equation:** The total sales equation is: $$5x + 3y = 98$$ 4. **Substitute known values:** $$5(10) + 3y = 98$$ $$50 + 3y = 98$$ 5. **Isolate $y$:** $$3y = 98 - 50$$ $$3y = 48$$ 6. **Solve for $y$:** $$y = \frac{48}{3}$$ $$y = 16$$ 7. **Interpretation:** The number of tomatoes sold is 16. **Final answer:** $$\boxed{16}$$