Answer:
250 minutes with the flat rate of $29.
[tex]x\leq 250[/tex]
x would be the number of minutes called.
[tex]x-250[/tex]
Tracy would be charged by $0.35 per minute.
[tex]f(x)=29\\ 0\leq x\leq 250[/tex]
[tex]f(x)=0.35(x-250)+29,\\250\leq x\leq ∞[/tex]