Build and use a linear cost model
Write a linear equation C = F + m*x for a flat-fee-plus-rate situation, then evaluate it or solve it for x. Unlimited questions, five difficulty levels, and a full worked solution every time — free.
Try one
Renting a kayak costs a flat $15.00 fee plus $3.00 per hour. Using C = 15 + 3x, find the total cost to rent it for 4 hours.
C = 15 + 3x
Answer: 27
See one solved, step by step
Renting a tutoring session block costs a flat $30.00 fee plus $8.00 per hour. Using C = 30 + 8x, find the total cost to book it for 5 hours.
C = 30 + 8x
📘 Worked solution
1C = 30 + 8xThis models the total cost: a fixed fee plus a per-hour rate.
2C = 30 + 8(5)Substitute x = 5 hours.
3C = 30 + 40 = 70Multiply first, then add the flat fee.
4Total cost: $70.00Round money to the nearest cent.
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