This can be calculated with some good old division and multiplication:
Step 1 - Divide the word count by the number of words every 2 minutes:
2000 ÷ 125 = 16
Step 2 - Multiply the 16 by the 2 minutes:
16 * 2 = 32
The 16 is the number of words it would take and multiply the 16 by 2 will tell us the number of minutes it would take for the whole document to be written.
Why? The triangle in the problem is an isosceles triangle. That means the two legs of the triangle are equal and the angle opposite to the equal legs are also equal. Therefore, angle C is also 74°. The sum of the interior angles of a triangle is equal to 180°. Thus, 180° = ∡A + ∡B + ∡C 180° = 74° + ∡B + 74° 180° = 148° + ∡B ∡B = 180° - 148° ∡B = 32°