a) \(\dfrac{15}{60}\) = \(\dfrac{1}{4}\) giờ ;
b) \(\dfrac{30}{60}\) = \(\dfrac{1}{2}\) giờ ;
c) \(\dfrac{45}{60}\) = \(\dfrac{3}{4}\) giờ.
d) \(\dfrac{20}{60}\) = \(\dfrac{1}{3}\) giờ ;
e) \(\dfrac{40}{60}\) = \(\dfrac{2}{3}\) giờ ;
g) \(\dfrac{10}{60}\) = \(\dfrac{1}{6}\) giờ;
h) \(\dfrac{5}{60}\) = \(\dfrac{1}{12}\) giờ.