Salut !
1 h 45 mn = 1 h + (45/60) h = 1 h + 3/4 h = 1,75 h
45 mn = 3/4 h = 0,75 h
1 h 20 mn = 1 h + (20/60) h = 1 h + 1/3 h = 4/3 h
vitesse = distance ÷ temps
= 245 ÷ 1,75
= 140 km/h
vitesse = distance ÷ temps
donc distance = vitesse × temps
= 140 × 0,75
= 105 km
et : distance = 140 × 4/3 = 186,66666..... km