Question

Any mathematical way to solve this question other than counting.

Answer 1

Yeas there is an easier formula. You can use the formula

x*{1+2+3+....+n+(n+1)} = x*[(n+1)+(n+2)]/2

Where n is the number of vertical lines forming a triangle and x being no of horizontal lines forming a triangle. I can dm you a link for similiar question if you want.

Answer 2

Answer:

28 is correct answer...