Ratios are like fractions. If we have 50 balloons and 30 are red and 20 are blue, the ratio of red to blue is 30:20, which can be reduced to 3:2 by dividing both parts of the ratio by the common factor 10. That's the same as saying 3 out of 5 balloons are red and 2 out of 5 balloons are blue. We add the two parts of the ratio together to find out how many objects there are, then we create the fractions 2/5 and 3/5 to express how many balloons there as fractions instead of ratios. Any clearer?