Question 935728


it should be {{{9}}}

as I see, there is a pattern: start in left vertices,subtract a number from second point, and add the number from third point, and put result in the middle 

first triangle: {{{(7-4)+9=3+9=12}}}
second triangle: {{{(1-1)+4=0+4=4}}}

third triangle: {{{(6-2)+5=4+5=9}}}