1)
7 * (х - 9) = 63
х - 9 = 63 : 7
х - 9 = 9
х = 9 + 9
х = 18
проверка:
7 * (18 - 9) = 63
7 * 9 = 63
63 = 63
2)
17 * (3х - 16) = 238
3х - 16 = 238 : 17
3х - 16 = 14
3х = 14 + 16
3х = 30
х = 30 : 3
х = 10
проверка:
17 * (3 * 10 - 16) = 238
17 * (30 - 16) = 238
17 * 14 = 238
238 = 238