Question

$5x + 2x=140$
$40x + 40x=160$
$14x + 2x + 5x=21$
$19x - 16x=21$

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Answer 1

5x + 2x = 140

7x = 140/7

x = 20

_____________

40x + 40x = 160

80 x = 160/80

x = 2

_____________

14x + 2x + 5x = 21

21x = 21/21

X = 1

_____________

19x16x = 21

3x = 21/3

x = 7