Answer:
66.7 cm
Explanation:
The focal length is half the radius of curvature, or f = 40 cm.
The image is real, so i = +100 cm.
The distance to the object is therefore:
1/o + 1/f = 1/i
1/o + 1/40 = 1/100
o = -66.7 cm
The object is 66.7 cm left of the mirror.
