Suppose that the number u were thinking about is x thus :
[tex] \frac{1}{4} x + \frac{1}{2} x = 12 \\ [/tex]
Multiply both sides by 4
[tex]4 \times ( \frac{1}{4} x + \frac{1}{2} x) = 4 \times 12 \\ [/tex]
[tex]x + 2x = 48[/tex]
[tex]3x = 48[/tex]
Divide both sides by 3
[tex] \frac{3x}{3} = \frac{48}{3 } \\ [/tex]
[tex]x = 16[/tex]
