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Math·Algebra·Linear equations in one variable

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A machine makes 3-inch, 7-inch, and 10-inch parts. During a certain day, the number of 3-inch parts that the machine makes is 5 times the number $n$ of 7-inch parts, and the number of 10-inch parts is 4. During this day, the machine makes 100 parts total. Which equation represents this situation?

A

$3(5n)+7n+10(4)=100$

B

$3n+7n+10n=100$

C

$5n+4=100$

D

$6n+4=100$