Hans is choosing between two exercise routines. In Routine #1, he does only running, burning 10.5 calories per minute. In Routine #2, he burns 18 calories walking. He then runs at a rate that burns 6.9 calories per minute. For what amounts of time spent running will Routine #1 burn at least as many calories as Routine #2? Use t for the number of minutes spent running, and solve your inequality for t.