We know that
[scale factor ]=[real]/[drawing]
[real]=[drawing]*[scale factor ]
step 1
find the real values
if the base of Riley's drawing is 10 centimeters
[real]=[drawing]*[scale factor ]--------> 10*3-------> 30 cm
the base of the triangular clock face is 30 cm
the height of Riley's drawing is 15 centimeters
[real]=[drawing]*[scale factor ]--------> 15*3-------> 45 cm
the height of the triangular clock face is 30 cm
the area of the triangular clock face is-----> 45*30/2-------> 675 cm²
the answer is the option C. 675 square centimeters
I THINK IS slove by factoring BUT I'M NOT SURE