Example Solving Word Problems: Cost Word Problem > Solving for Quantities

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What You Enter

One day, Mrs. Jones paid $18.70 for 4 kilograms of brown rice and 3 kilograms of white rice. On another day, she paid $13.30 for 2 kilograms of white rice and 3 kilograms of brown rice. If the prices were the same on each day, find the price per kilogram for each type of rice.

What You Get

Let B = Cost of each KILOGRAMS of BROWN RICE in dollars
Let W = Cost of each KILOGRAMS of WHITE RICE in dollars
 
4B + 3W = 18.7
3B + 2W = 13.3
 
B = (18.7 - 3W)/4
 
3(18.7 - 3W)/4 + 2W = 13.3
 
3(18.7 - 3W) + 4(2)W = 4(13.3)
 
56.1 - 9W + 8W = 53.2
 
-1W = -2.9
 
W = $ 2.9
 
B = (18.7 -3(2.9))/4
 
B = $ 2.5

Solution: B = $ 2.5