A player has to score an average of 18 points and above over 5 rounds of a game to qualify for the next level.

Round	Score
One	20
Two	15
Three	25
Four	15
Five	?

What is the lowest score Mathew can get in the fifth round in order to qualify for the next level? Ans: ___

1. Calculate the minimum total score required over 5 rounds

$\text{Total score needed} = 18 \times 5 = 90$

2. Calculate the total score obtained in the first four rounds

$\text{Current total} = 20 + 15 + 25 + 15 = 75$

3. Find the lowest score needed in the fifth round

$\text{Lowest score} = 90 - 75 = 15$