First, find the least common multiple of 3 and 4, the denominators. You find that lcm(3,4)=12.
So, we get [tex]\frac{1}{3}*\frac{4}{4}+\frac{1}{4}*\frac{3}{3}=\frac{7}{12}[/tex]
This is because the denominator must the a multiple of the lcm in order to add the fractions properly.
