Sara's brother drove 47.5% of the trip, and didn't for the rest of the 52.5% Sara drove 80% of the remainder of what her brother's drove, so she drove 80% of the 52.5%. To know how much she drove from the total trip, we multiply 80% by 52.5%. Remember that the percentage is a fraction over 100. 80% * 52.5% = (80/100) * (52.5/100) = 4200/10000 = 0.42 Then to transform it to a percentage, we multiply the answer by 100 and get 42. So Sara drove 42% of the trip. Let x by the duration of the whole trip, and let's use the rule of three: 4 hours and 12 minutes = 4*60 + 12 = 240 + 12 = 252 minutes.
