Sao à

23. Much _scientific_ work requires a good knowledge of mathematics. (science)

26. His _decision_ to retire surprised us all. (decide)

28. Many people find it _ waste _ to advertise. (waste)

30. He looks thin, but _actually_ he is very healthy, (actual)

32. He did some old jobs at home _disappointedly_ (disappoint)

35. He was _successful_ in his job. (succeed)

42. They’ve got a _satisfied_ result. (satisfy)

43. Carbon dioxide occurs in the air in _naturally_ form. (nature)

44. Children are _naturally_ to overcome problems. (determine)

45. They got the _successful_ of being successful in life. (satisfy)

46. He is young man with great _Expectations_ (expect)

47. I like your new _ calculating_ machine. (calculate)

48. May I borrow your _calculator_ ? (calculate)

50. We must make _provision_ for our old age saving money. (provide)

*Đáp án*

a, 15 - (3 + x) = 4                         b, -11 - (19 - x) = 50

           3 + x = 15 + 4                                  19 - x = -11 + 50

           3 + x = 19                                         19 - x = 39

             x     = 19 - 3                                           x = 19 + 39

            x      = 16                                                 x = 58