Answer:
Julia and her husband should buy 20 pounds of City Roast coffee and 30 pounds of French Roast coffee.
Explanation:
Let x be the amount of City Roast coffee and y be the amount of French Roast coffee. We know that:
x + y = 50 (total amount of coffee is 50 pounds)
14.80x + 4.80y = 250 (total cost of the blend is $250)
5.00(x + y) = 250 (the blend should cost $5.00 per pound)
From the last equation, we have 5.00x + 5.00y = 250, which can be rearranged as:
5.00x - 250 = -5.00y
Now we can substitute the second equation into the first equation to find the amount of City Roast coffee:
14.80x + 4.80y = 250
14.80x + 4.80y = 250
14.80x - 250 = 4.80y - 5.00y
14.80x - 250 = -0.20y
y = (14.80x - 250) / -0.20
Substituting this expression for y into the first equation, we get:
x + (14.80x - 250) / -0.20 = 50
Solving for x, we find that x = 20.
Therefore, Julia and her husband should buy 20 pounds of City Roast coffee and 30 pounds of French Roast coffee.