159382

My answer is 21.

I got answer by using Guess, Check and improve. First I started trying to find what is the circle, I guessed until I reached 4 and saw that it means that the square is 8 and the triangle is 6. Then I tried to figure out what the hexagon is. So I looked at the line with 2 hexagons and 2 squares. 2 squares are 16 so the remaining is 14. Split that and that means the hexagon is 7. 2 circles, 1 hexagon and 1 triangle is 21. 4 + 4 + 7 + 6 = 21.