We can solve this problem using cross-multiplying method.
We have following information
18 points = 40%
We need to find out the final score. Let's use x for final number of points.
x points = 100%
We can write this:
18 points = 40%
x points = 100%
We cross multiply numbers
18*100=x*40
1800=40x /:40
1800/40=x
x=45
The final score was 45 points.