maths

Q1
The no. "4" should replace the questionmark because:
17 + 8 = 5 × 5
13 + 7 = 5 × 4
6 + 12 = 6 × 3
10 + 6 = 4 × (4)

Q2
3 is the greatest possible number of acute angles that a convex 2010-gon can have. / A convex 2010-gon can have at most 3 acute angles.

Reason:
Let n be the greatest possible number required.
n × 90° + (2010 - n) × 180° > 180° (2010 - 2)
∴ n < 4

The sum of exterior angles of a convex polygon = 360°

So at most 360/90 - 1 = 3 obtuse angles among exterior angles ,

therefore at most 3 acute angles it can have.