What the slope of this please help :)

Christina can paint 420 square feet in 105 minutes. which unit rate describes the scenario?

What is the domain of the of the exponential function shown below?

Edith is shopping for a new leather couch. jordan’s furniture has one that costs $3,000. however, this weekend she can get a 15% discount. how much money will edith save if she buys the couch this weekend? a $15b $2,550c $45,000d $450