Okay so 8 (hector) - 3(Mary) = 5 years apart
So, 16 (hector) - 5 (years apart) = 11 (Mary’s age)
Right triangle because a2<span> + b</span>2<span> = c</span><span>2</span>
Here how i found my answer.
Answer: 
Step by step:

(Used a table of common angles)
A. 8 pages per hour because 120 (2 hours) ÷15=8
b. $40÷15 (pages)=$2.70 (rounded)