1/3х + 1/х = 4/15
5+15=4х
20=4х
х=5
проверка 1/15+1/5=1/15+3/15=4/15
1/х - 1/7х = 2/7
7-1=2х
2х=6
х=3
проверка 1/3-1/21=7/21-1/21=6/21=2/7
1/4х + 1/х = 5/16
4+16=5х
5х=20
х=4
проверка 1/16+1/4 = 1/16+4/16=5/16
1/х - 1/9х = 2/9
9-1=2х
2х=8
х=4
проверка 1/4-1/36=9/36-1/36=8/36=2/9
1/8х +1/х = 3/8
1+8=3х
3х=9
х=3
проверка 1/24+1/3=1/24+8/24=9/24=3/8
1/х - 1/5х = 2/15
15-3=2х
2х=12
х=6
проверка 1/6-1/30=5/30-1/30=4/30=2/15