Answer:
Now, let x equal the number:
10 times the number is 10x.
Sum of 10 times the number and 15, means sum of 10 times the number plus 15, which is 10x + 15.
Eleven times the same number, means 11 times x, which is 11x.
Sum of 10 times a number and fifteen is added to eleven times the same number is therefore: 10x + 15 + 11x = 21x + 15
Explanation: