In adding and subtracting fractions with unlike denominators, you have to get a least common denominator which is exactly like the least common multiple it just so happens to be in the denominator.

2nd level Maths and Numeracy Fractions and decimals learning resources for adults, children, parents and teachers.

Save guides, add subjects and pick up where you left off with your BBC account. When two fractions have the same value, but have different denominators and numerators, they are called equivalent ...