For Part A, the answer would be 49+0.89c. That is because in order to get the centrepieces delivered it would take 49 dollars no matter the amount she buys and then depending on the amount of centrepieces she would buy, it would be multiplied by 0.89.
For part B, I believe the answer is 405. That is because we plug in the amount of 400 into the equation as c.
49+0.89(400)
49+356
=405
