12 * (1 3/4 х + 5/8) = 8 1/2
12 * (7/4х + 5/8) = 17/2
7/4х + 5/8 = 17/2 : 12
7/4х + 5/8 = 17/2 * 1/12
7/4х + 5/8 = 17/24
7/4х = 17/24 - 5/8
7/4х = 17/24 - 15/24
7/4х = 2/24
7/4х = 1/12
х = 1/12 : 7/4
х = 1/12 * 4/7
х = 1/3 * 1/7
х = 1/21
12 * ( 1 3/4 * 1/21 + 5/8) = 8 1/2
12 * (7/4 * 1/21 + 5/8) = 17/2
12 * (1/4 * 1/3 + 5/8) = 17/2
12 * (1/12 + 5/8) = 17/2
12 * (2/24 + 15/24) = 17/2
12 * 17/24 = 17/2
1/1 * 17/2 = 17/2
17/2 = 17/2
8 1/2 = 8 1/2