1 Take the total number of sweets as the unit 1, which was originally 4/5 of the total. After removing 10g, it became 7/ 12 of the total, which was 4/5-7/ 12 less.

So the formula is10/(4/5-7/12) =160/13.

2 1080/6= 180 km, which is the sum of speeds.

180 * 5/9 =100km

180/4/9 = 80km