(х-5) / 4 = 7 - (2х - 11)/3
(х-5) / 4 = 21/3 - (2х-11)/3
(х-5) / 4 = (21-(2х-11))/3
(х-5) / 4 = (21-2х+11)/3
(х-5) / 4 = (32-2х)/3
3(х-5) / 4 = 32-2х
3(х-5) = 4(32-2х)
3х-15 = 128-8х
3х+8х=128+15
11х=143
х=13
5+ (7х-12)/3 = х+13
15/3 + (7х-12)/3 = х+13
(15+(7х-12))/3=х+13
15+(7х-12)=3(х+13)
15+7х-12=3х+39
3+7х=3х+39
7х-3х=39-3
4х=36
х=9