well, the number is x, hmmm well, whatever% of anything is just (whatever/100) * anything, therefore, 25% of x is just (25/100) * x.
[tex] \bf \stackrel{\textit{two-thirds of 24}}{\cfrac{2}{3}\cdot 24}~~=~~\stackrel{\textit{25\% of \underline{x}}}{\cfrac{25}{100}\cdot x}\implies \cfrac{48}{3}=\cfrac{25x}{100}\implies 16=\cfrac{x}{4}\implies 64 [/tex]
