Answer:
1:150
Step-by-step explanation:
Hello
the scale factor is the ratio that exists between the measurements of a map with the originals ,the scale is the relationship between the real dimensions and those of the drawing that represents reality on a plane or a map.the scale factor is dimensionless
for a map a scale of reduction is used

Step 1
the scale factor of 2 centimeters : 3 meters means that, if we measure 2 cm in the map , it is 3 meters on the reality
Let
Length on the reality=3 m
Length on the =2 cm
replacing

to cancel units is need convert cm into m, or m
1 m =100 cm
3m = x? cm
x=3*100 cm
x=300 cm
Step 2
replacing

the scale factor is 150, usually is written 1:150, that means that any length in the plane must be multiplied by 150 to know the length in reality
Have a great day