To calculate the ratio, we simply reason the problem out. A ratio relates both quantities in a proportional way. In this case, we have 6 yellow tomatoes and 7 orange tomatoes. This means that for every 6 yellos tomatoes we have orange tomatoes. This is equivalent to the ratios 6:7 or 7:6. In this case, it is not correct to sum both quantities (6+7 =13) since they are from two different types we want to relate through the ratio. The notation 6:7 is equivalent as having 6/7.