Х - часы езды по шоссе
х + 0,5 - часы по просёлочной дороге
40 (х + 0,5 ) + 60 х =240
40 х + 20+ 60 х = 240
100 х = 220
х = 2,2
У=-5х+4
К=-5
М=4............
3 3/4 +1 1/2 = 3 3/4 + 1 2/4 = 4 5/4 = 5 1/4
2 5/6 - 1 5/12 = 2 10/12 - 1 5/12 = 1 5/12
4 - 1 2/3 = 3 3/3 - 1 2/3 = 2 1/3
3 2/7 - 6/7 = 2 9/7 - 6/7 = 1 3/7
1 1/3 * 4 = 4/3 * 4 = 16/3 = 5 1/3
3 1/4 * 2/5 = 13/4 * 2/5 = 13/2 * 1/5 = 13/10 = 1,3
2 1/2 : 3 = 5/2 : 3 = 5/2 * 1/2 = 5/4 = 1 1/4
20 : 2 1/2 = 20 : 5/2 = 20 * 2/5 = 4 * 2 = 8