First, identify the ratio: 1:50 (1 foot on the model is 50 feet on the house) to find the actual height of the window multiply 1 1/5 by 50 *= 300/5 simplifies into 60 the height of the real window is 60 feet
72-62=9 (grow 9 inches in 3years) In a year it grows 3 inches (9/3) Find how much it grows in 20 years: 3*20=60 inches Then just add the 60 inches to the original height er 63+60=123 inches