a) 18/15 + 7/15+12/15 = 18/15 + 12/15 +7/15
= 30/15+ 7/15
= 37/15
b) 9/7+8/7 + 11/7 = 9/7 + 11/7 + 8/7
= 20/7 + 8/7
= 28/7
a) \(\frac{18}{15}+\frac{7}{15}+\frac{12}{15}=\frac{18}{15}+\frac{12}{15}+\frac{7}{15}=\frac{30}{15}+\frac{7}{15}\)\(=\frac{37}{15}\)
b)\(\frac{9}{7}+\frac{8}{7}+\frac{11}{7}=\frac{9}{7}+\frac{11}{7}+\frac{8}{7}=\)\(\frac{20}{7}+\frac{8}{7}=\frac{28}{7}\)