What do erosion and deposition have in common?

Which formula can be used to calculate the molar mass of ammonia (nh3)? molar mass of n + molar mass of h 3 × molar mass of n + molar mass of h molar mass of n + 3 × molar mass of h 3 × molar mass of n + 3 × molar mass of h

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The chart shows the bid provided by four contractors to complete a job. which contractor is the most cost-effective?