Natasha = 30 * 7 = <<30*7=210>>210 minutes
Esteban = 10 * 9 = <<10*9=90>>90 minutes
Total = 210 + 90 = <<210+90=300>>300 minutes
300 minutes = <<300/60=5>>5 hours
Natasha and Esteban exercised for a total of 5 hours.
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