`a )`
`A = 450 × 0,45 + 1,5 × 30 × 3 + 5 × 9 × 2,5`
`A = 4,5 × 45 + 45 × 3 + 45 × 2,5`
`A = 45 × ( 4,5 + 3 + 2,5 )`
`A = 45 × 10`
`A = 450`
`---`
`B = 0,75 + 1/2 - 50% + 2 : 1/2 + 1 1/2 - 3/4`
`B = 0,75 + 0,5 - 0,5 + 4 + 3/2 - 3/4`
`B = 1,25 - 0,5 + 4 + 3/2 - 3/4`
`B = 0,75 + 4 + 3/2 - 3/4`
`B = 4,75 + 3/2 - 3/4`
`B = 4,9 - 3/4`
`B = 4,15`
`b )`
`1/3 + 1/6 + x/4042 = 1`
`1/2 + x/4042 = 1`
`x/4042 = 1 - 1/2`
`x/4042 = 1/2`
`x/4042 = 2121/4042`
`=> x = 2021`
`---`
`2 × x + 3 × x + 5 × x - 7 × x = 24`
`x × ( 2 + 3 + 5 - 7 ) = 24`
`x × 3 = 24`
`x = 24 : 3`
`x = 8`
`#dtkc`