`1/3` + `4/5` = `17/15`
`3/5` : `2/3` = `3/5` x `3/2` = `9/10`
`1/3 + 4/5 = 5/15 + 12/15 = 17/15`
`3/5 : 2/3 = 3/5 xx 3/2 = 9/10`
a) \(\dfrac{1}{3}\) + \(\dfrac{4}{5}\) = \(\dfrac{5}{15}\) + \(\dfrac{12}{15}\) = \(\dfrac{17}{15}\)
b) \(\dfrac{3}{5}\) : \(\dfrac{2}{3}\) = \(\dfrac{3}{5}\) x \(\dfrac{3}{2}\) = \(\dfrac{9}{10}\)