`a, 24 . 82 + 24 . 18 - 100`
`= 24 . (82 + 18) - 100`
`= 24 . 100 - 100`
`= 2400 - 100`
`= 2300`
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`b, 13 + 3 . [39 - (5 - 2)^{2}]`
`= 13 + 3 . [39 - 3^{2}]`
`= 13 + 3 . [39 - 9]`
`= 13 + 3 . 30`
`= 13 + 90`
`= 103`
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`c, 127 - {15 + [2^{2} . 2^{3} - 3^{20} . (7^{2} - 49)]}`
`= 127 - {15 + [2^{2} . 2^{3} - 3^{20} . (49 - 49)]}`
`= 127 - {15 + [2^{2} . 2^{3} - 3^{20} . 0]}`
`= 127 - {15 + [4 . 8 - 0]}`
`= 127 - {15 + [32 - 0]}`
`= 127 - 47`
`= 80`
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`d, 6 . 3^{2} + 2^{2} . 3^{2}`
`= 6 . 9 + 4 . 9`
`= 9. (6 + 4)`
`= 9. 10`
`= 90`
