the cost of renting a car is 35/wk plus $0.25/mi traveled during that week. An equation to represent the cost would be y = 35+0.25, where the x is the number of miles traveled. what is your cost in dollars if you travel 60 mi?

Your "y = 35+0.25" would be better if written as y = $35/wk + ($0.25/mile) x, where x is the # of miles traveled and we assume that you rent the car for 1 week or less.

Now let's evaluate y = $35/wk + ($0.25/mile) x for x = 60 mi:

y = $35/wk + ($0.25/mile) (60 miles) = $35/wk + $15 = $50 total.