Hey there!
Vick had 7/10 bucket of water. . . .
She used some of the water and now has 3/10 left . . .
Subtracts the numbers 7 and 3 to solve this:
7 - 3 = 4 <----
The correct answer to your question should be 4/10 of a bucket.
Vick used 4/10 of the bucket to wash the car.
Hope this helps you.
Have a great day!