GMAT Critical Reasoning (CR) | Re: Over an eleven-month period, during which national retail co

CAn someone explain the appraoch to tackle this question? Thanks.

Over an eleven-month period, during which national retail computer sales remained stable at 400,000 units per month, sales by the Friendly Computer Stores chain rose 200 percent, increasing the chain’s share of the total market to 7 percent. Other retail stores tried, without success, to attract customers away from the Friendly chain. Then regulation X was imposed on all computer retailers by the federal government. In the ensuing