“…Second, proportional missing-value problems with an integer ratio (i.e., the ratio between two numbers forms an integer number, e.g., 4:2) are easier to solve than those with a noninteger ratio (i.e., the ratio between two numbers forms a noninteger number, e.g., 6:4; Kaput & West, 1994; Karplus et al, 1983; Riehl & Steinthorsdottir, 2019; Tourniaire & Pulos, 1985). Third, enlarge problems, in which the target is bigger than the given situation so that there is an increase in quantities, are easier to solve than shrink problems, in which the target is smaller than the given situation so that there is a decrease in quantities (Riehl & Steinthorsdottir, 2014, 2019).…”