There are two factories in a small town, and both of them emit carbon dioxide into the air. Currently factory 1 emits 120 tons per month, whereas factory 2 currently emits 180 tons per month. The technology used by each factory is different, leading to varying costs for reducing emissions. Factory I's costs of reducing emissions by X1 is given by C1(x] ) = x], while factory 2's costs of reducing emissions by X2 is given by C2 ( X2 ) = -2 + 20. Suppose the government in this town would like to cut monthly total emissions to half of the current level. To achieve that, the government has decided to impose a tax on each ton of pollution per month emitted by a factory. How should the government set the tax to achieve its desired goal