Stage 8 - Q10 - 5 marks
18526
Challenge: service A has fixed fee USD 12 and rate USD 4 per km. Service B has unknown fixed fee and rate. Its graph passes through \(\left(1,\ 11\right)\) and crosses A at \(\left(5,\ 32\right)\). Find B’s rule and explain which is cheaper on either side of the crossing.
Hint
The intersection supplies a second point on the unknown line.