Answer: $1.25
Step-by-step explanation:
Let the cost of cracker be a.
Let the cost of cookies be b.
Let the cost of candy bars be c.
From the question,
6a + 6b + 6c = $21
8a + 5b + 10c = $26
5a + 4b + 7c = $18.50
To solve this, we first pick any two pairs of equation. This will be:
6a + 6b + 6c = $21 ....... i
8a + 5b + 10c = $26 ....... ii
Multiply equation i by 8
Multiply equation ii by 6
48a + 48b + 48c = $168 ....... iii
48a + 30b + 60c = $156 ....... iv
Subtract equation iv from iii
18b - 12c = 12
We then pick another two pairs
8a + 5b + 10c = $26
5a + 4b + 7c = $18.50
Multiply equation i by 5
Multiply equation ii by 8
40a + 25b + 50c = $130
40a + 32b + 56c = $148
Subtract the equations
-7b - 6c = -18
Then, solve the new equations formed
18b - 12c = 12 ....... v
-7b - 6c = -18 ....... vi
Multiply equation i by -7
Multiply equation ii by 18
-126b + 84c = -84
-126b - 108c = -324
Subtract the equations
192c = 240
c = 240/129
c = $1.25
From equation v, put the value of c
18b - 12c = 12
18b - 12($1.25) = 12
18b - $15 = $12
18b = $27
b = $27/18
b = $1.5
Since,
6a + 6b + 6c = $21
6a + 6($1.5) + 6($1.25) = $21
6a + $9 + $7.5 = $21
6a + $16.5 = $21
6a = $21 - $16.5
6a = $4.5
a = $4.5/6
a = $0.75
One candy bar cost $1.25
