Draw a diagram to illustrate the problem as shown below. The length of baseboard needed is AB + BC + CD + DE + FE. Note that 30 in = 30/12 ft = 2.5 ft.
Because of the door opening, AB + EF = 12 - 2.5 = 9.5 ft Also, BC = DE = 10 ft CD = 12 ft.
The amount of baseboard needed is AB + BC + CD + DE + FE = (AB + EF) + BC + CD + DE = 9.5 + 10 + 12 + 10 = 41.5 ft