From the Table of 15, we know that:
15 times 6 is equal to 15 multiplied by 6, which equals 90.
15 times 3 is equal to 15 multiplied by 3, which equals 45.
Therefore, the sum of 15 times 6 and 15 times 3 is equal to 15 multiplied by 6 plus 15 multiplied by 3, which simplifies to 90 plus 45, resulting in a final answer of 135.