The first problem is modeled by the following inequality:
[tex]40+5x\ge95-4x[/tex]
The second problem is represented by
[tex]95+4x<40+5x[/tex]
The third problem is represented by
[tex]95-4x<40+5x[/tex]
Observe that, "spending" refers to subtraction, "earnings" refers to addition. Also, the variables represent time. Additionally, "less than" is expressed as "<", "as much as or more than" is expressed as >=.
