CLUE 12 SOLUTION
The paintings should be separated into 17 groups of three. Each group of three will contain one painting from the circle group, one from the square group, and one from the triangle group.
Each painting in a triplet will have something in common with the other two paintings, either style, subject matter or artist.
Each painting is numbered. Sum the three numbers, then find the letter represented by the sum (modulo 26 = keep subtracting 26 from the sum until you have a number between 1 and 26). Substitute A for 1, B for 2, ... Y for 25 and Z for 26.
When you are done, arrange the letters in order by the sum of the original three numbers, starting with the lowest sum, and going to the highest.
The answer spells
PULGAS WATER TEMPLE