(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Three truck drivers went into a roadside cafe. One truck driver purchased four sandwiches, a cup of coffee and ten doughnuts for $8.45. Another drivers purchased three sandwiches, a cup of coffee and seven doughnuts for $6.3. What did the third truck driver pay for a sandwich, a cup of coffee and a doughnut?

2. Relevant equations

3. The attempt at a solution

The system's equations are:

4s + 1c + 10d = 8.45

3s + 1c + 7d = 6.3

1s + 1c + 1d = a

The system has infinite solutions, right? There are 4 variables for 3 equations. I can't determine a.

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# [Linear Algebra] - Resolving a system

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