"Published in Vacaville, California, USA"
A customer in a coffee shop wishes to purchase a blend of two coffees: Kenyan, costing $ 3.50 a pound, and Sri Lankan, costing $ 5.60 a pound. He ends up buying 3 lbs of such as blend, which costs him $11.55. How many pounds of each kind went into the mixture?
Solution:
From the description of a given word problem, it is an application of linear equation with two equations, two unknowns.
Let x be the number of pounds of Kenyan coffee
y be the number of pounds of Sri Lankan coffee
From the statement "He ends up buying 3 lbs of such as blend,..", then the working equation is
From the statement "A customer in a coffee shop wishes to purchase a blend of two coffees: Kenyan, costing $ 3.50 a pound, and Sri Lankan, costing $ 5.60 a pound....which costs him $11.55.", then the working equation is
Hence, the working equations for the given problem are
From the first equation,
Substitute the value of x to the second equation, we have
Substitute the value of y to any of two equations, we have
Therefore, a customer needs to buy a mixture of 2.5 pounds of Kenyan coffee and 0.5 pounds of Sri Lankan coffee that cost $11.55.