Answer
36lb of meat, 50 lb of potatoes and 21lb of carrots are needed.
Work Step by Step
1. Get the factor to increase the mass of each ingredient by can be determined by $200\div140=\frac{10}{7}$
2. The mass of each ingredient required to serve 200 people is determined by multiplying the factor with the original individual mass of each ingredient.
Mass of meat:$\frac{10}{7}\times25=35.714...\approx36$
Mass of potatoes:$\frac{10}{7}\times35=50$
Mass of carrots:$\frac{10}{7}\times15=21.428...\approx21$