How many 3-digit numbers can be formed if repetition is
allowed?

up to 999

Step-by-step explanation: Now, if you consider repetition allowed, all the numbers from 100 to 999 are 3 digit numbers. How many numbers are formed ? count numbers starting from 100 up to 999. Hence, 900 numbers are formed.

option a is correct.

step-by-step explanation:

scale factor: it is used to find proportional measurements.

proportions means having the same ratio.

scale factor is the ratio of the model measurement to the actual measurement in a simplest form.

or we can say that the ratio of any two corresponding lengths in two similar geometric figures

if the scale factor is more than 1, then it is an enlargement,

if the scale factor less than 1, then it is a reduction.

given the two geometric figure:

by definition of proportions, we have

ca = ec

cpctc makes it so that corresponding parts of the triangle you proved to be equal are equal, the other options aren't part of the part of the triangles you proved to be equal.