SOLUTION: Write a system of two equations in two unknowns. On Monday, Archie paid $3.40 for three doughnuts and two coffees. On Tuesday he paid $3.60 for two doughnuts and three coffees. On

Question 982091: Write a system of two equations in two unknowns.
On Monday, Archie paid $3.40 for three doughnuts and two coffees. On Tuesday he paid $3.60 for two doughnuts and three coffees. On Wednesday he was tired of paying the tab and went out for coffee by himself. What was his bill for one doughnut and one coffee?
Answer by Cromlix(4381) (Show Source): You can put this solution on YOUR website!
Hi there,
Make doughnuts = x
and coffees = y
3x + 2y = 3.40.....(1)
2x + 3y = 3.60.....(2)
Multiply (1) by 3
and (2) by 2
9x + 6y = 10.20.....(1)
4x + 6y = 7.20......(2)
Subtract (2) from (1)
5x = 3.00
x = 0.60
Substitute x = 0.60 into (2)
2x + 3y = 3.60
2(0.60) + 3y = 3.60
1.20 + 3y = 3.60
3y = 3.60 - 1.20
3y = 2.40
y = 0.80
Doughnut = $0.60
Coffee = $0.80
Hope this helps:-)
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