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
The difference between 90% and 72% is 18%
Answer: 9 * (5 - y)
Explanation:
Times: multiplication
Difference: subtraction
y: the unknown variable
65÷455= 7
Hope this helps!