1) Distribute the 3 to the 7x and the 12 using the distributive property. Then simplify:
3(7x - 12) + 26 = 3x - 10
21x - 36 + 26 = 3x - 10
21x - 10 = 3x - 10
2) Get all the variables to one side of the equation and everything else to the other side:
21x - 10 = 3x - 10
18x - 10 = -10
18x = 0
x = 0
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Answer: x = 0