Young mathematicians

Question and answers of the week.
1. When you reverse the digits of the number 13, the number increases by 18. How many other two digit numbers increase by 18 when their digits are reversed?
Answer: 6 other two-digit numbers excluding 13 are possible.

2. Which number replaces the question mark


Answer: 9
The number at the centre of each triangle equals the sum of the lower two numbers minus the top number.