3×c=15. 7×y+9=51. 26+(72÷y)=35

3 × c = 15

c = 15 / 3

c = 5

7 × y + 9 = 51

7y = 51 - 9

7y = 42

y = 42 / 7

y ≈ 6 (приблизительно)

26 + (72 ÷ y) = 35

72 ÷ y = 35 - 26

72 ÷ y = 9

y = 72 / 9

y = 8