The price of a 2-hour plumbing repair job is $100 and the price of a 5-hour job is $190. Write an equation for the cost C of a t-hour repair job and use the equation to find the cost of a repair job lasting 6 hours.

Question

anonymous · Answer

@hartnn

dumbcow · Answer

C = x*t + k
where x is hourly rate and k is some fixed cost

plug in the 2 given points to get 2 equations in which to solve for x and k
100 = 2x + k
190 = 5x + k

by subtracting equations you get rid of the k
--> 90 = 3x  
--> x = 30

solving for k
100 = 2(30) + k
--> k = 40

C = 30t + 40

anonymous · Answer

how about this one Bill travels west on Interstate 80 from Summerville. Sally leaves Carlton City and travels on I-80 in the same direction as Bill. Bill's distance in miles from Metro City is given by B(t) = 120 – 70t and Sally's distance in miles from Metro City is given by S(t) = 135 – 80t, where t is the number of hours since noon. Write an expression for the distance separating Bill and Sally and find their separation at 4:00 PM.@dumbcow

anonymous · Answer

@dumbcow