Answer:

Step-by-step explanation:
Let
c -----> the additional amount (in dollars) David will spend
we know that
The word " at most" in this context means "less than or equal to"
The amount David has spent plus possible additional amounts he will spend must be less than or equal to $39
so
The inequality that represent this situation is

solve for c
subtract 22 both sides


The maximum amount he could spend is $17
Answer:
2009.6 and 13824 minutes and 230.4 hours
Step-by-step explanation:
v=3.14 x 4 x 2 x 80= 2009.6
No solution exists for -3x+y=-18 and -3x+y=-6