if you look at the question we have equations as

2+9=711

14+6=820;

17+11=628

then 12+3=??

from Equation 1 

2+9=711

2+9=(2-9)(2+9)

= 711

here we used a formula called a+b=(a-b)(a+b)

similarly for remaining equations

Equation:2

14+6=(14-6)(14+6)=820

Equation:3

17+11=(17-11)(17+11)=628

now we have 12+3=??

12+3=(12-3)(12+3)=915

12+3=915 is the correct answer

Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry’s standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum

Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry’s standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum