so, 3 liters of water, add 1/2 liter of lemonade, that's 3 and 1/2 liters of lemonade.
so in short, how many times does 1/3 go into 3 and 1/2?
let's change the mixed to "improper" and divide then.
[tex]\bf \stackrel{mixed}{3\frac{1}{2}}\implies \cfrac{3\cdot 2+1}{2}\implies \stackrel{improper}{\cfrac{7}{2}}\\\\
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\cfrac{\quad \frac{7}{2}\quad }{\frac{1}{3}}\implies \cfrac{7}{2}\cdot \cfrac{3}{1}\implies \cfrac{21}{2}\implies 10\frac{1}{2}[/tex]
