Y is the sum of two parts one constant and partly varies with the time spent.it costs 180 naira for 2 hrs and 450 naira for 7 hrs
a. Write an equation connecting cost x and time t
b.find the cost for 10 hrs
x = kt + c
when x = 180, t = 2
so 180 = 2k + c
when x = 450, t = 7
so 450 = 7k + c
subtract the 2 equations,
270 = 5k
k = 54
then 180 = 108 + c , or c = 72
x = 54t + 72
when t = 10
x = 540+72 = 612