$#min$
`a) x + 20,11 = 45 × 1,25`
` x + 20,11 = 56,25`
` x = 56,25 - 20,11`
` x = 36,14`
`b) (30 - x) : 5 + 7 = 9`
`(30 - x) : 5 = 9 - 7`
`(30 - x) : 5 = 2`
`(30 - x) = 2 × 5`
`30 - x = 10`
`x = 30 - 10`
`x = 20`
`c) x + 75% × 4 = 1993`
` x + 0,75 × 4 = 1993`
`x + 3 = 1993`
`x = 1993 - 3`
`x = 1990`
`d)` $\dfrac{x+5}{45}$ `= 7/9`
$\dfrac{x+5}{45}$ `= 35/45`
`x + 5 = 35`
` x = 35 - 5`
`x = 30`
