3 4/15: ((2 3/4х+ 4 1/2): 21 3/7)-1 1/8=5 7/8
3 4/15:((2 3/4х+4 1/2):21 3/7)=5 7/8+1 1/8
3 4/15:((2 3/4х+ 4 1/2): 21 3/7=7
(2 3/4х+4 1/2):21 3/7=3 4/15:7
(2 3/4х+4 1/2): 21 3/7=7/15
2 3/4х+4 1/2=7/15•21 3/7
2 3/4х+4 1/2=10
2 3/4х=10-4 1/2
2 3/4х=11/2
х=11/2:2 3/4
х=2
Ответ 2