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What is the smallest whole number larger than the perimeter of any triangle with a side of length $12$ and a side of length $13$? (adapted from 2015 AMC8, Question 8) 
Overseas Competition->Knowledge Point->Calculation Modules->Basic Concepts of Equation->Inequalities
We know from the triangle inequality that the last side, $s$, fulfills $s\textless12+13=25$. Adding $12+13$ to both sides of the inequality, we get $s+12+13\textless25$, and because $s+12+13$ is the perimeter of our triangle, (B) 50 is our answer. 