Fraction is nothing but the part of the whole. Adding the fractions with the like denominators is a simple process. But adding fractions with unlike denominators involves a few steps calculation. Foremost thing is to turn the unlike into like denominators. For doing so, we must take LCM (least common multiple). Here is the free online Adding Three Fractions Calculator to add 3 fractions with same/different denominators.
Add 3 fractions with different denominators for the values a1 as 5, a2 as 4, a3 as 3, b1 as 7, b2 as 8 and b3 as 7.
lcm = LCM (b1, b2, b3)
Sum of Fractions = (a1*(lcm/b1) + a2*(lcm/b2) + a3*(lcm/b3)) / lcm