7) Three roommates: Steven, Lisa, and Tim, share an apartment. It is very cold outside, and they are considering turning up the thermostat in the apartment by 1, 2, 3, or 4 degrees. Their individual marginal benefits from making it warmer in the apartment are as follows: Steven Lisa Tim 1 degree $25 $20 $15 2 degrees $20 $15 $10 3 degrees $15 $10 $5 4 degrees $10 $5 $0 Each time they raise the temperature by 1 degree, the bill goes up by $35. By how many degrees should they raise the temperature? Explain your