Answer: Unit rate = 4/35 of a gallon per hour
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Work Shown:
3 & 1/2 = 3 + 1/2
3 & 1/2 = 6/2 + 1/2
3 & 1/2 = (6+1)/2
3 & 1/2 = 7/2
The faucet drips 2/5 of a gallon in 7/2 hours
2/5 gallon : 7/2 hours
2*(2/5 gallon) : 2*(7/2 hours) ..... multiply both sides by 2
4/5 gallon : 7 hours
(1/7)*(4/5 gallon) : (1/7)*(7 hours) ... multiply both sides by 1/7
4/35 gallon : 1 hour
The unit rate is 4/35 of a gallon per hour.
"Per hour" means "every 1 hour".