Can you help me solve for both questions, and show the step by step process please for the first one I got -1.375 but I don't think that's correct. Thank you for your time!

Could somebody me with this radical simplification?

Which statement is true about a number and its additive inverse? a. their product is always one. b. their sum is always one. c. they are always reciprocals of each other. d. their sum is always zero.

When a valve is open 281 gallons of water go through it in one hour the number of gallons that would go through in 94 hours is