A map is drawn to a scale 0f 1 :20 000. Calculate the area of a a lake that measures 3 square km

Answer 1

1 meter/20,000 meters

is 1 meter/20 km

square that for area instead of length
1 meter^2/400 km^2

so (3/400) square meter
or in centimeters
1 sq meter = 10,000 sq cm
so
30,000/400 = 300/4 = 75 cm^2