write the total costs a linear function in the form
[tex]y=mx+b[/tex]in which:
y= total cost
x= number of months
m= charge per month
b= fixed start up fee
replace all data in the equation
[tex]\begin{gathered} y=50\cdot x+200 \\ y=50x+200 \end{gathered}[/tex]Since the question is the cost for 1 month, x=1
[tex]\begin{gathered} y=50(1)+200 \\ y=250 \end{gathered}[/tex]The cost for the use of the cellphone is $250
