Simplify. 18x + 3xy + 5y −2(6xy − 2y + 4) A) 18x − 9xy + 9y − 8 B) 18x + 9xy + 9y − 8 C) 18x + 9xy − 9y + 8 D) 18x − 9xy + y − 8
2 answers:
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Answer:
Each pencil costs $0.07 and each eraser costs $0.03
Step-by-step explanation:
System of linear equations
It refers to the study of systems when n variables are related in m linear equations, each one is not independent from the others. Solving such systems can be done following very diverse approaches.
Let p=the price of each pencil while e is the price each eraser
Julio bought 4 pencils and 3 erasers, spending
David bought 3 pencils and 4 erasers, spending
The system of equations is written in the form
We'll solve it by reduction. Multiplying the first equation by -3 and the second by 4:
Adding both equations:
7e=0.21
e=0.03
Multiplying the first one by -4 and the second by 3
Adding both equations:
-7p=-0.49
p=0.07
Solution: Each pencil costs $0.07 and each eraser costs $0.03