Ahmed needs to decide whether his company needs to install new production system. If he does, the new system will bring cash benefit of $200,000 over the next 3 year while the current system will contribute $125,000 over the same period. The new system costs $150,000 and the current system can be sold for $8,000 now. Calculate a) Marginal benefit b) Marginal cost c) Should Ahmed install new system?