Johnathan has been on a diet since January 2013 . so far , he has been losing weight at a steady rate . Based on monthly weigh-ins , his weight , W , can be modeled by the function w=-3m+205 where m is the number of months after January 2013 .

a)how much did Johnathan weigh at the start of the diet ?
b)how much weight has Johnathan been losing each month ?
c)how many months did it take Johnathan to lose 45 pounds ?