To add fractions, the denominators have to be the same. 12 is the least common multiple between 3 and 4 so we should multiply the numerator and denominator of both fractions with a number that will make the denominator 12. Then, add the numerators.
Instead of asking on Brainly go on Google and search up Symbolab just see the calculator website and see how it is it can solve an algebraic equation and it tells you how step by step and when I mean step by step I mean every STEP!