№1
2/15÷(1/5х-1/3)-1/12=1/24
2/15÷(1/5х-1/3)=1/24+1/12
2/15÷(1/5х-1/3)=1/24+2/24
2/15÷(1/5х-1/3)=3/24
2/15÷(1/5х-1/3)=1/8
1/5х-1/3=2/15÷1/8
1/5х-1/3=2/15×8/1
1/5х-1/3=16/15
1/5х-1/3=1 1/15
1/5х=1 1/15+1/3
1/5х=1 1/15+5/15
1/5х=1 6/15
1/5х=1 2/5
х=1 2/5÷1/5
х=7/5÷1/5
х=7/5×5/1
х=7
2/9÷(5/9х-1/2)+1/7=1/3
2/9÷(5/9х-1/2)=1/3-1/7
2/9÷(5/9х-1/2)=7/21-3/21
2/9÷(5/9х-1/2)=4/21
5/9х-1/2=2/9÷4/21
5/9х-1/2=2/9×21/4
5/9х-1/2=1/3×7/2
5/9х-1/2=7/6
5/9х-1/2=1 1/6
5/9х=1 1/6+1/2
5/9х=1 1/6+3/6
5/9х=1 4/6
5/9х=1 2/3
х=1 2/3÷5/9
х=5/3×9/5
х=1/1×3/1
х=3