Verified answer

7x + 21 = 100 - 16

7x = 100 - 16 - 21

7x = 63

x = 9

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x : 121 - 1265 = 3647

x : 121 = 3647 + 1265

x : 121 = 4912

x = 4912 * 121

x = 594352

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787x - 7286 = 20259

x = (20259 + 7286) : 787

x = 27545 : 787

x = 35

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120 + 3x = 375

x = (375 - 120) : 3

x = 255 : 3

x = 85

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24000 : (x - 12) = 80

x = (24000 : 80) + 12

x = 300 + 12

x = 312

_____________

x : 26 + 1654 = 2610

x = (2610 - 1654) * 26

x = 956 * 26

x = 24856