GK 2018 Q5
5. The two numbers \(a\) and \(b\) both lie between −5 and 10 inclusive. What is the largest possible value of \(a - b\)?
- A −5
- B 0
- C 10
- D 15
- E 20
Grey Kangaroo 2018, Question 5. © UK Mathematics Trust. Original paper on ukmt.org.uk
Answer: D 15
The largest possible value of \(a - b\) comes from subtracting the smallest possible value of \(b\) from the largest possible value of \(a\). Hence the largest possible value is 10 − (−5) = 10 + 5 = 15.
Solution © UK Mathematics Trust, from the GK 2018 solutions.