To solve the problem, we need to set up equations based on the information provided:
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The equation for the remaining ice cream in the vanilla machine after \( x \) days is: \[ 180 - 20x \] where 180 is the initial amount of ice cream and 20 is the amount sold per day.
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The equation for the remaining ice cream in the chocolate machine after \( x \) days is: \[ 140 - 16x \] where 140 is the initial amount of ice cream and 16 is the amount sold per day.
We want to find the value of \( x \) when the quantities of ice cream left in both machines are equal: \[ 180 - 20x = 140 - 16x \]
Now, let's solve this equation:
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Rearrange the equation: \[ 180 - 140 = 20x - 16x \] which simplifies to: \[ 40 = 4x \]
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Divide both sides by 4: \[ x = 10 \]
This indicates that after 10 days, both machines will have the same amount of ice cream left.
The correct response from the provided options is: \[ 180 - 20x = 140 - 16x ; x = 10 \]