he answer would be x = 3.
15x = 10x + 21 - 6 (Subtract 6 from both sides)
15x = 10x + 15 (Simplify 10x + 21 - 6 to 10x + 15)
15x - 10x = 15 ( Subtract 10x from both sides)
5x = 15 ( Simplify 15x - 10x to 5x )
x = 15/5 ( Divide both sides by 5 )
x = 3 ( Simplify 15/5 to 3 ).
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