4целое4/5÷(3х-2,5)=4/17 20/21+9/14-2/7

4 4/5 : (3х -2,5)=4/17
3х-2,5=4/17 : 4 4/5=4/17 * 5/24
3х -2,5=5/102
3х=5/102+2,5=5/102 +2 1/2
3х=5/102 + 2 51/102
3х=2 56/102=2 28/51
х=2 28/51 : 3=130/51 *1/3
х=130/153

.
20/21 +9/14 -2/7=40/42+27/42 - 12/42=55/42=1 13/42