A t-shirt costs $12 per t-shirt plus $3 shipping. Write the equation that describes the total cost c for the number of t-shirts purchase t.
so equation
c = 3 + 12t
if t = 1 then c(cost) = 3 + 12(1) = 3 + 12 = 15
if t = 2 then c(cost) = 3 + 12(2) = 3 + 24 = 27
if t = 3 then c(cost) = 3 + 12(3) = 3 + 36 = 39
if t = 4 then c(cost) = 3 + 12(4) = 3 + 48 = 51
