Under one plan, the first 30 min of any phone call costs only 3.5 cents per minute. The charge increases to 7.5 cents per minute thereafter. The information can be written in the form of a piecewise-defined function. Where 'C' represents the cost and 'm' represents the minutes. 3.5m ;0sms30 C = 7.5m - 120; m > 30 3.5m; 0sms 30 C = 7.5m; m > 30 3.5m; 0 30