509.
1. 3 2/20-х=18 1/8
3.1-х=18.125
-х=18.125-3.1=15.025
х=-15.025=-15 1/40
2. - 10 3/7-х=-9 2/3
-х=-9 2/3+10 3/7=-29/3+73/7=-203/21+219/21=16/21
х=-16/21
3. 3 1/2-х=7 1/5
-х=7 1/5-3 1/2=36/5-7/2=72/10-35/10=37/10=3 7/10
х=-3 7/10
4. 40 5/9-х=63 4/5
-х=63 4/5-40 5/9=319/5-365/9=2835/45-1825/45= 1010/45=22 20/45=22 4/9
х=-22 4/9
511.
1. (8 1/42-12 4/21)-(5 1/42-3 3/7)= 8 1/42-12 4/21- 5 1/42+3 3/7=8 1/42-5 1/42-12 4/21+24/7= 3-256/21+72/21= 3-328/21=3-15 13/21=-13 8/21