To find the area of EFDC, first we have to find the area of ΔAEF, ΔEBC and rectangle ABCD
Area of ΔAEF = 12× Base × Height
= 12 × 6 × 10
= 1 × 3 × 10
= 30 cm2
Area of ΔEBC = 12× Base × Height
= 12 × 8 × 10
= 1 × 4 × 10
= 40 cm2
Area of rectangle ABCD = length × breadth
= 18 × 10
= 180 cm2
Then,
Area of EFDC = Area of ABCD – (ΔAEF + ΔEBC)
= 180 – (30 + 40)
= 180 – 70
= 110 cm2