Translate the following statement into an appropriate algebraic statement: the number of text messages sent times $0.15 plus the number of minutes talked times $0.07 less a $2.50 discount will give the total cost for the cell phone bill this month.

a) $0.15t + $0.07m - $2.50 = c

b) t + m = $2.50

c) $0.15m + $0.07t = $2.50

d)$0.15m + $0.07t - $2.50 = c