3,4 * 19,5 - 0,3 * 2/3 * (3 1/2 - 2 1/3) = 66 1/15
1) 3 1/2 - 2 1/3 = 3 3/6 - 2 2/6 = 1 1/6
2) 3,4 * 19,5 = 66,3
3) 0,3 * 2/3 = 3/10 * 2/3 = 2/10 = 1/5
4) 1 1/6 * 1/5 = 7/6 * 1/5 = 7/30
5) 66,3 - 7/30 = 66 3/10 - 7/30 = 66 9/30 - 7/30 = 66 2/30 = 66 1/15