Answer:
Explanation:
The <em>average</em> is the mean. It is calculated adding all the values and dividing the sum by the number of values (data):
For the students who took the test the day before you, you can write:

Where n is the number of students who took the test first.
Thus, when the average was 69 the equation is:

When you take the test, the n + 1, the new average is 70, and the sum of the scores raised in 95 points:

Now you have a system of two equation and two unknowns, so you can solve it.
Clear the sum of the scores from the first equation:

Subsitute in the second equation:

Solve for n:

Thus, when you include your self the number of students who took the test was 25 + 1 = 26.