by jhduHU
(COACIPC)
A burger place sells burgers (b) for $4, and fries (f) for $2. If bob bought six items for a total of $18, how many did he buy of each?
Solution
A system of linear equations can be used to solve this problem.
Let b be the number of burgers bob bought
Let f be the number of orders he placed for French fries
Then, we can come up with the following two equations
4b + 2f = 18 (equation 1)
b + f = 6 (equation 2)
Solve for b in equation 2. We can do this by subtracting f from both sides of the equation
b + f - f = 6 - f
b = 6 - f
Replace b with 6 - f in equation 1
4 (6 - f) + 2f = 18
4x6 - 4xf + 2f = 18
24 - 4f + 2f = 18
24 - 2f = 18
24 - 18 = 2f
6 = 2f
f = 3
Since b = 6 - f, b = 6 - 3 = 3
Therefore, Bob ordered 3 items each