Teresa likes to talk on the telephone. We can symbolize her preferences with utility function U(B;C) = 10B +5J, where J and B are the minutes of conversation per month with the Jackie and Bill respectively. Calculate the formula for her indifference curve to get the U units of utility? Determine her marginal rate of substitution of minutes talking to Jackie for minutes talking to Bill? Explain what types of goods are represented with this utility function?