1. You look for an expression like [tex] ax+b [/tex], where [tex]a,b[/tex] are any number you want. For example, if you choose [tex] a=14 [/tex] and [tex] b=25 [/tex] you'll end up with
[tex] 14x+25 [/tex]
14 is the coefficient, x is the variable, 25 is the constant. The word phrase would be something like "add 25 to 14 times a number".
2. No, the expression has two terms: [tex] 4[/tex] and [tex] 3n^2 [/tex] The terms are the parts of an expression separated by "+".