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suppose that 12 inches of wire costs 36 cents.At the same rate, how many inches of wire can be bought for 21 cents?

 Nov 19, 2015

Best Answer 

 #2
avatar+26393 
+10

suppose that 12 inches of wire costs 36 cents.At the same rate, how many inches of wire can be bought for 21 cents?

 

\(\small{ \begin{array}{rcll} \dfrac{ 12\ \text{inches} } { 36\ \text{cents} } \cdot 21\ \text{cents} &=& \dfrac{12}{36}\cdot 21 \ \text{inches} \\\\ &=& \dfrac{1}{3}\cdot 21 \ \text{inches} \\\\ &=& \dfrac{21}{3} \ \text{inches} \\\\ &=& 7 \ \text{inches of wire} \\\\ \end{array} } \)

laugh

 Nov 19, 2015
edited by heureka  Nov 19, 2015
 #1
avatar+87 
+5

12  = x

36  = 21

 

 

Cross multiply

12*21=36x

252=36x

Divide 36 on both sides

7=x

7 inches of wire

 Nov 19, 2015
 #2
avatar+26393 
+10
Best Answer

suppose that 12 inches of wire costs 36 cents.At the same rate, how many inches of wire can be bought for 21 cents?

 

\(\small{ \begin{array}{rcll} \dfrac{ 12\ \text{inches} } { 36\ \text{cents} } \cdot 21\ \text{cents} &=& \dfrac{12}{36}\cdot 21 \ \text{inches} \\\\ &=& \dfrac{1}{3}\cdot 21 \ \text{inches} \\\\ &=& \dfrac{21}{3} \ \text{inches} \\\\ &=& 7 \ \text{inches of wire} \\\\ \end{array} } \)

laugh

heureka Nov 19, 2015
edited by heureka  Nov 19, 2015

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