(y+21):7=23, 124:(y−3)=31, 36:z+11=23​

(y + 21) : 7 = 23

y + 21 = 161

y = 161 - 21

y = 140

124 : (y - 3) = 31

124 = 31 × (y - 3)

4 = y - 3

- y = - 3 - 4

- y = - 7

y = 7

36 : z + 11 = 23

36 : z = 23 - 11

36 : z = 12

12z = 36

z = 3