take three circle....and these circle are..... both corner circle of the bottom row and the top row circle.

and place it as i tell you

After took circles

1.now first bottom row have only two circle then place one circle in the last in the middle of these two.

2. Now you see first bottom row have one circle and second one have two circle and third one have three circles and top one have two circles.

3 . Now top row have already two circles and left two circle arrange on the corner of the top row.

Now see triangle downward looking