Well, there are 60 minute in an hour and 60 seconds in a minute so we can multiply 7 by 60 and then 60 again to find out answer. 7 times 60=420 times 60=25200 she babysat for 25200 seconds
First, we get the area of each tile: (100 cm = 1m) .20 m* .15 m = 0.03m^2 Then, we solve for the total area of the wall: 5m*3m= 15m^2 Then we divide 15/0.03 = 500 tiles
