c, 625 - 522 : ( 54 - x ) = 596
⇔ 522 : (54 - x ) = 625 - 596
⇔ 522 : (54 - x ) = 29
⇔ (54 - x ) = 522 : 29
⇔ 54 - x = 18
⇔ x = 54 - 18
⇔ x = 36
⇒ x = 36
d, 97 - 27 . (25 - 3 . x)^5 = 2² . 5² - 30
⇔ 97 - 27 . (25 - 3 . x)^5 = 70
⇔ 27 . (25 - 3 . x)^5 = 97 - 70
⇔ 27 . (25 - 3 . x)^5 = 27
⇔ (25 - 3 . x)^5 = 27 : 27
⇔ (25 - 3 . x)^5 = 1
⇔ 25 - 3 . x = 25 - 1
⇔ 25 - 3 . x = 24
⇔ x^5 = 24 : 3
⇔ x = 8
⇒ Vậy x = 8
