The arithmetic mean of two numbers is 49. The first number is 7. What is the second number?

Let x2 denote the unknown second number.

In the initial data for this task, it is reported that if the first number is added to the second number and the resulting sum is divided by two, the result should be the number 49.

Since, according to the condition of the problem, number one is equal to seven, we can draw up the following equation:

(7 + x2) / 2 = 49,

solving which, we get:

7/2 + x2 / 2 = 49;

7/2 + x2 / 2 – 7/2 = 49 – 7/2;

x2 / 2 = 98/2 – 7/2;

x2 / 2 = 91/2;

(x2 / 2) * 2 = (91/2) * 2;

x2 = 91.

Answer: the 2nd number is 91.