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A restaurant serves sandwiches and salads. They sold 7 sandwiches and 7 salads for a total of $140 for lunch. In the evening, 21 sandwiches and 77 salads were sold for a total of $700. Let w represent the cost of a sandwich and d represent the cost of a salad.

Part A
Write and equation that represents the total cost at lunch time:
Write an equation that represents the total cost in the evening:

Part B
Find the cost of each sandwich (w ) using your system of equations above:

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amna04352

Answer:

A) 7w + 7d = 140

21w + 77d = 700

B) $15

Step-by-step explanation:

7w + 7d = 140

w + d = 20

d = 20 - w

21w + 77d = 700

3w + 11d = 100

3w + 11(20 - w) = 100

3w + 220 - 11w = 100

120 = 8w

w = 15

aaaamnaaah

Hey there,

Here is what we know based on the question given:

  • sold 7 sandwiches and 7 salads for $140
  • sold 21 sandwiches and 77 salads for $700

Now that we know that we can answer Part A of the question given:

  • Lunch time: 7w + 7d = 140
  • Evening: 21w + 77d = 700

Since we have the equations now we can solve Part B:

  1. Multiply the lunch time equation by 11 to cancel out one variable:                  11(7w + 7d = 140) = 77w + 77d = 1540
  2. Now we use the new equation to subtract the two to solve for w:              (77w + 77d = 1540) - (21w + 77d = 700) = (56w = 840) w = 15  

Since we have to solve for the sandwiches we now have the cost per sandwich has to be $15.

Hope I helped,

Amna

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