21) $8 \times \frac{15}{5}-(5+9)$

Step 1 ：Calculate the fraction: \(\frac{15}{5} = 3\)

Step 2 ：Multiply the result by 8: \(8 \times 3 = 24\)

Step 3 ：Add 5 and 9: \(5 + 9 = 14\)

Step 4 ：Subtract the sum from the product: \(24 - 14 = 10\)

Step 5 ：\(\boxed{10}\)