Ans 2:
Class : Class 6
in the 1st figure 3 matchsticks make 1 whole triangle 3 triangles are there in 1st figure means 9 matchsticks in total. In 2nd figure 6 triangles are there means 18 matchsticks in total. In 3rd figure 9 triangles are there means 27 matchsticks in total. Now the series is 9, 18, 27 you are increasing by 9. So 27 plus 9 is 36. You got pattern 4 so add 18 and 36 which is 54