# 1Multiple Choice58×415=\frac58\times\frac{4}{15}=85×154=14\frac144115\frac155116\frac166117\frac1771
# 4Multiple Choice1718×1112=ab\frac{17}{18}\times\frac{11}{12}=\frac{a}{b}1817×1211=ba다. a+b=?401402403404
# 7Multiple Choice112113×112117=ab\frac{112}{113}\times\frac{112}{117}=\frac{a}{b}113112×117112=ba라면 a+b는?15765257653576545765