First part:
Since, Dawn pays $32.00 a month, plus $0.75 for each minute over the allowed minutes in her plan.
Let 'm' be the extra minutes used by Dawn over the allowed minutes in her plan.
So, Total bill = [tex]\$32 +(\$ 0.75 \times m)[/tex]
Total bill of Dawn = [tex]\$(32+0.75m)[/tex]
So, the expression which shows Dawn's bill for one month is:
[tex]\$(32+0.75m)[/tex]
Second part:
Dawn received a bill for $47.00 last month.
Since, the expression for Dawn's bill for one month is:
Total bill = [tex]\$32+\$0.75m[/tex]
[tex]\$47 = \$32+\$0.75m[/tex]
[tex]\$ 47 - \$32 = \$0.75m[/tex]
[tex]\$15 = \$0.75m[/tex]
[tex]m = 20[/tex]
Therefore, Dawn used 20 minutes her phone beyond the allowed minutes.