Answer:
a) 1/2; reduction
b) 5/4; enlargement
Explanation:
In each case, the scale factor is CP'/CP. When it is more than 1, the dilation is an enlargement.
Even before you run the numbers, you can tell if it is an enlargement or not. If the dilated figure is larger, P is closer to C than is P'. If P' is closer to C, then it is a reduction.
a) CP'/CP = (4-2)/4 = 2/4 = 1/2 . . . . a reduction
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b) CP'/CP = 25/20 = 5/4 . . . . an enlargement