А) 1/4+1/5

To solve the addition problem 1/4 + 1/5, you need to find a common denominator. The least common multiple of 4 and 5 is 20.

To convert 1/4 to have a denominator of 20, you multiply the numerator and denominator by 5: (1/4) * (5/5) = 5/20

To convert 1/5 to have a denominator of 20, you multiply the numerator and denominator by 4: (1/5) * (4/4) = 4/20

Now that both fractions have the same denominator, you can add them together: 5/20 + 4/20 = 9/20

So, 1/4 + 1/5 = 9/20.