450:[41-(2x-5)]=3 mũ 2 . 5 (5x-39).7+3=80 15.5. (x-35)-525=0 [3.(70-x)+5]:2=46

+, 450 : [41 – (2x – 5)] = $3^{2}$ . 5

⇔ 450 : [41 – 2x + 5] = 9 . 5

⇔ 450 : [46 – 2x] = 45

⇔ 46 – 2x = 10

⇔ 2x = 36

⇔ x = 18

+, (5x – 39) . 7 + 3 = 80

⇔ (5x – 39) . 7 = 77

⇔ 5x – 39 = 11

⇔ 5x = 50

⇔ x = 10

+, 15 . 5 . (x – 35) – 525 = 0

⇔ 75 . (x – 35) = 525

⇔ x – 35 = 7

⇔ x = 42

+, [3 .(70 – x) + 5] : 2 = 46

⇔ 3 .(70 – x) + 5 = 92

⇔ 3 .(70 – x) = 87

⇔ 70 – x = 29

⇔ x = 41