25 * (7/10 + 3/5 + 1/2) = 45
1) 7/10 + 3/5 = 7/10 + 6/10 = 13/10 = 1 3/10
2) 1 3/10 + 1/2 = 1 3/10 + 5/10 = 1 8/10 = 1 4/5
3) 25 * 1 4/5 = 25 * 9/5 = 5 * 9 = 45
5 : 1 1/4 + 7 : 1 1/3 = 9 1/4
1) 5 : 1 1/4 = 5 : 5/4 = 5 * 4/5 = 4
2) 7 : 1 1/3 = 7 : 4/3 = 7 * 3/4 = 21/4 = 5 1/4
3) 4 + 5 1/4 = 9 1/4