Topic on game theory

Adam and Lucy are two Hainan Chicken Rice sellers in the same food court. Every week, each of them will submit a price to the food court committee to fix the weekly set meal price. Initially they agree to set at a same high price for each set meal but one might submit a lower price to attract more customers in that week. The payoff matrix is as follows: Unit: (\$ Thousands) Assume both players use a grim strategy. Is it worthwhile for one of them to defect once, given the weekly total rate of return r=0.2 ? Explain