Arithmetic Expressions Follow

Hello, 

Could somente help me?

I´m new in mps and i´d like to write simple arithmetic expressions, like  

a =  10; b = 10;

a + b = 20

a - b = 0

a * b = 100

a / b = 1

I tried to learn watching videos on the site, but i couldn´t understand. 

Tks!