389+(х-47)=819 900÷а=180÷4 (х+631)-567=666

Question

389+(х-47)=819 900÷а=180÷4 (х+631)-567=666

Answer 1

389+(х-47)=819
389+х-47=819
х=819-389+47
х=477

900÷а=180÷4
900÷а=45
а=900÷45
а=20

(х+631)-567=666
х+631-567=666
х=666-631+567
х=602