Ta có: 2 giờ 40 phút = \(\frac{8}{3}\)giờ
Theo đề bài, ta có:
\(\frac{8}{3}giờ:y=\frac{5}{7}giờ\)
\(\Rightarrow y=\frac{8}{3}:\frac{5}{7}\)
\(y=\frac{56}{15}\)
Vậy\(2giờ40phut:\frac{56}{15}=\frac{5}{7}\)
2h40' = \(\frac{8}{3}\)h
-> y = \(\frac{8}{3}\): \(\frac{5}{7}\)= \(\frac{56}{15}\)( hay 3h44')