Respuesta :

you can see x on both sides are congruent
input 21 on one side to get: 5 times 21 minus 12 =93
input 21 on side two :3 times 21 plus 30=93
both sides = 93 and are congruent
The answer is 21, both 5x-12 and 3x+30 equal 93 when x is substituted with 21.
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