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Ace and Sam were painting a house. Ace painted $$\frac{3}{10}$$ of the house. Sam painted $$\frac{2}{10}$$ more than Ace. What fraction of the house still needs to be painted? 
Overseas Competition->Knowledge Point->Calculation Modules->Fractions
Sam: $$\frac{2}{10}+\frac{3}{10}=\frac{5}{10}$$  Total: $$\frac{5}{10}+\frac{3}{10}=\frac{8}{10}$$  Left: $$\frac{10}{10}-\frac{8}{10}=\frac{2}{10}$$ 