Hello I am happy to help you with this problem. So the formula to solve for a triangle is A = bxh divided by 2.
So it’s area equals base times height divided by 2. So the base is 2 1/2 which becomes 5/2 ( five over 2) times 2 which equals 5. It’s because you cancel. So 5 divided by 2 equals 5/2 which also equals 2 1/2.
I hope that helps you. If you have any questions please feel free to ask me.