a) 24 - x : 5 = 3
=>x : 5 = 24 - 3
=>x : 5 = 21
=>x = 21 . 5
=>x = 105
b) 36 - 6 . (x + 4) = 12
=>6 . (x + 4) = 36 - 12
=>6 . (x + 4)=24
=>x + 4=24 : 6
=>x + 4 = 4
=>x = 4 - 4
=>x = 0
c) 40 - (2x - 18) : 3= 28
=>(2x - 18) : 3 = 40 - 28
=>(2x - 18) : 3 = 12
=>(2x - 18) = 12 . 3
=>(2x - 18) = 36
=>2x = 36 + 18
=>2x = 54
=>x = 54 : 2
=>x= 27
d) (2x - 1) : 3 = 2^4 + 3^2
=>2x - 1 : 3 = 16 + 9
=>(2x - 1) : 3=25
=>2x - 1 = 25 . 3
=>2x - 1 = 75
=>2x = 75 + 1
=>2x =76
=>x = 76 ÷ 2
=>x = 38
g) (x - 4) . (x + 5)= 0
=>x - 4 . x + 5 = 0
=>x . (-4 + 5) = 0
=>x . (-1) = 0
=>x = 0 : (-1)
=>x = 0
