All u need is here in the pic

for problem 1 it is 2nd one

for problem 2 1200 people bought online cause 15*1200= 18000 18000+2500= 20500 so it would be 3rd one 550

then problem 3 would be 4th one 72

Step-by-step explanation:

the problem 2 one is confusing so it might be wrong hope not cross fingers!!!

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