1.
83,6-(х+2,705)=1,895
х+2,705=1,895-83,6
х+2,705=−81,705
х=-81,705+2,705
х=−79
2.
(х-15,8)+31,209=42,9
х-15,8=42,9-31,209
х-15,8=−28,309
х=-28,309+15,8
х=−12,509
