Toni rows a boat at 4.5 km/per hour upstream and then turns around and rows 5.5 km/per hour back downstream to her starting point. if her total rowing time is 48 minutes for how long does she row upstream

Respuesta :

4.5x-5.5y=0, x+y=48
y=48-x, 4.5x-5.5(48-x)=0
4.5x+5.5x=48*5.5
10x=264
x=26.4 minutes