[tex]p\%=\dfrac{p}{100}\\\\40\%=\dfrac{40}{100}=\dfrc{4}{10}=0.4\\\\n-a\ number\\\\40\%\ of\ a\ number\to0.4n\\\\The\ equation:\\\\n+0.4n=126\\\\1.4n=126\qquad\text{divide both sides by 1.6}\\\\\boxed{n=90}\\\\Answer:\ The\ number\ is\ equal\ 90.[/tex]
