How to find common denominator

The decision of mathematical tasks with fractions has many ways. One of the simplest and most common operations - addition/subtraction of fractions. If the denominator of both fractions are the same, just folded/subtract the values in the numerator, but if the numbers in the denominators are different, come to the aid of finding the lowest common denominator.

Instruction

1. Find a common denominator is that when multiplying two we add/subtracted fractions for any numbers in the denominators have the same value. This would allow to add and subtract fractions easily, using only the numerators.
   Example:6/7+4/5.Denominators do not match, so we need to find numbers that when you multiply them by each of the fractions would lead them to a common multiplier. For the first fraction is the number 5 and 7 for the second.
2. Now you need to multiply the numerator and denominator of each fraction to the corresponding multiplier. Turns out:30/35 + 28/35 = 58/35 = 1,657 (decimal)