Solve the Fraction Addition: 3/5 + 1/4 Step by Step

Fractions represent parts of a whole. You can only add fractions when they have the same-sized parts (same denominator). Adding 3/5 + 1/4 = 4/9 is like trying to add 3 fifths to 1 fourth without converting to equal parts first!

Find the smallest number that both denominators divide into evenly. For 5 and 4:

• Multiples of 5: 5, 10, 15, 20...
• Multiples of 4: 4, 8, 12, 16, 20...

Use the same process! Find multiples of each denominator until you find the first common one. If the numbers don't share common factors, you can also multiply the denominators together as a quick LCD.

Yes, always check if your answer can be simplified! Look for common factors in the numerator and denominator. Since 17 and 20 share no common factors, $\frac{17}{20}$ is already in lowest terms.

You can use any common denominator, but using the LCD makes your work easier! Other common denominators (like 40, 60, 80) will give you larger numbers that you'll need to simplify at the end.

Convert your answer back to a decimal and check: $\frac{17}{20} = 0.85$. Also check: $\frac{3}{5} = 0.6$ and $\frac{1}{4} = 0.25$. Does 0.6 + 0.25 = 0.85? Yes! ✓