84 17 、 On the map with a scale of 0.3060.90 km, the distance between the two places is 12 cm. A and B vehicles start from both places at the same time and run in opposite directions. After 3 hours, they meet. It is known that the speed ratio of a and B vehicles is 7:5, so the speed of the two vehicles can be calculated

84 17 、 On the map with a scale of 0.3060.90 km, the distance between the two places is 12 cm. A and B vehicles start from both places at the same time and run in opposite directions. After 3 hours, they meet. It is known that the speed ratio of a and B vehicles is 7:5, so the speed of the two vehicles can be calculated

Scale 0 30 60 90 km scale 1:3000000
12 × 3000000 = 36000000 (CM) = 360 (km)
360÷3=120
120÷(7+5)=10
10 × 7 = 70 (km / h) - A
10 × 5 = 50 km / h