I only need question C. I'm not sure how to calculate this answer. please explain. thank you!

Pan American Refineries, headquartered in Houston, must decide among three sites for the construction of a new oil-processing center. The firm has selected the six factors listed below as a basis for evaluation and has assigned rating weights from 1 to 5 on each factor. Subhajit Chakraborty, the CEO, has rated each location for each factor on a 1 to 100 point basis. In the table below, the rating weights and the rating value for each of the locations on the factor are presented: Location A Location B Location C Rating Weight 5 70 80 80 Factor Factor Description 1 Proximity to port facilities 2 Power-source availability and cost 3 Workforce attitude and cost 2 85 65 95 4 50 65 70 4 Distance from Houston 2 15 85 65 5 2 100 55 80 Community desirability Equipment suppliers in area 6 3 55 55 85 a) Based on the given information, the best location for Pan American Refineries is Location with a total weighted score of 1,415 (Enter your response as an integer.) b) If Location B's score for Proximity to port facilities was reset at 90, it will have a new total weighted score of 1,285 (Enter your response as an integer) c) Location B will lower its ranking as soon as its score (within the confines of the 1 to 100 point basis) on Proximity to port facilities is less than (Enter your response as an integer)