Question

Find the area of the blue region

Answer 1

SA of a rectangle: length * width

Find SA of the blue rectangle: 15 km * 13 km = 195 km

Find SA of the white rectangle: 9 km * 6 km = 54 km

Subtract white rectangle from blue rectangle: 195 - 54 = 141

Area of blue region:
`\boxed {141~km^2}`

Answer 2

Remark

The area of the blue region = the entire area - the white region

Givens

Area of blue region = ???

Area of the white region = 6 * 9

Whole area = 13 * 15

Answer

Area of blue region = 13 * 15 - 6 * 9

Area of blue region = 195 - 54

Area of blue region = 141 <<<< Answer