



 
Hi Nancy. Let P = the time that Peter takes to mow one lawn. After 18 minutes, Charles has mowed 18/C lawns. After 18 minutes mowing together, the team has mowed 18/C + 18/P lawns. Thus, 18/C + 18/P = 1. When mowing a lawn, Peter takes 15 minutes longer than Charles, so P = 15 + C. Can you use the substitution method and solve these two equations for C? Cheers,  


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