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put this solution on YOUR website!Let x be the first even number. Then x+2 and x+4 are the other two. Their sum is 144, so
x + (x+2) + (x+4) = 144
3x + 6 = 144
3x = 138
Here, x is the variable, 138 is a constant, and 3 is the coefficient. Solving for x should be easy.