Lesson 4: Proportional Relationships a 2. A recip Equations the qu a. Let's write equations describing proportional relationships. b. 4.1: Number Talk: Division Find each quotient mentally. C. 645 - 100 645:50 48.6 - 30 48.6 + x

Move the decimal point of 645 two units left ( You are dividing by 100)
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[tex]\frac{645}{50}=\frac{129}{10}=12.9[/tex]Simplify 645/50 as 129/10, now move the decimal point of 129 one unit left (You are dividing by 10).
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[tex]\frac{48.6}{30}=\frac{243}{\frac{5}{30}}=\frac{243}{150}=\frac{81}{50}[/tex]Express 48.6 as 243/5, then use division of fractions to get 243/150, then simplify 243/150 as 81/50
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[tex]\frac{48.6}{x}=\frac{\frac{243}{5}}{x}=\frac{243}{5x}[/tex]Express 48.6 as 243/5, then use division of fractions to get 243/5x