The phrase "share sum" can be easily replaced with other words that convey similar meanings. For example, instead of saying "share sum," you could use phrases like "split the cost," "divvy up the expenses," "distribute evenly," or "apportion the bill." These synonyms are helpful in situations where multiple people are jointly responsible for paying a shared expense, such as splitting the check at a restaurant or dividing the cost of rent between roommates. By using synonyms for "share sum," you can make your language more interesting and varied while still expressing the same idea clearly and effectively.