1) 58 4/15 - 56 7/24 = 874/15 - 1351/24 = 874*8/15*8 - 1351*5/24*5 = 6992/120 - 6755/120 = 237/120 = 79/40
2) 1 21/40 + 0.225 = 61/40 + 225/1000 = 61*5/40*5 + 225/1000 = 12525/1000 + 225/1000 = 1750/1000 = 7/4
3) 8 3/4 * 3/5 = 35/4 * 3/5 = 21/4
4) 7/4 / 21/4 = 7/4 * 4/21 = 1/3
5) 79/40 / 8/10 = 79/40 * 10/8 = 79/32
6) 79/32 + 1/3 = 79*3/32*3 + 32/32*2 = 237/96 +32/96 = 269/96 = 2 77/96