Let \( x \) represent the number of minutes that have passed.
For the first vat, which starts empty and is filling at a rate of 6 gallons per minute, the amount of liquid in the vat after \( x \) minutes can be expressed as:
\[ \text{Amount in first vat} = 6x \]
For the second vat, which starts with 10 gallons and continues to fill at a rate of 4 gallons per minute, the amount of liquid in this vat after \( x \) minutes can be expressed as:
\[ \text{Amount in second vat} = 10 + 4x \]
To find when the two vats will have an equal amount of liquid, we can set the two expressions equal to each other:
\[ 6x = 10 + 4x \]
Now, we can solve this equation for \( x \):
- Subtract \( 4x \) from both sides:
\[ 6x - 4x = 10 \]
- Simplify:
\[ 2x = 10 \]
- Divide by 2:
\[ x = 5 \]
So, after 5 minutes, both vats will have an equal amount of liquid.
To summarize, the equation representing when the two vats will have equal amounts of liquid is:
\[ 6x = 10 + 4x \]
And they will be equal after \( x = 5 \) minutes.