20. Find the total cost. car selling price: $\$ 9800$ tax rate: $7 \%$

Step 1 ：Given the selling price of the car is \(\$ 9800\) and the tax rate is \(7 \%\).

Step 2 ：The total cost of the car would be the selling price plus the tax.

Step 3 ：The tax can be calculated by multiplying the selling price by the tax rate, which is \(9800 \times 0.07 = 686\).

Step 4 ：Adding the tax to the selling price gives the total cost, which is \(9800 + 686 = 10486\).

Step 5 ：Final Answer: The total cost of the car is \(\boxed{10486}\).