Rectangle a has length of 12 and width 8. rectangle b has length 15 and width 10. rectangle c has length 30 and width 15. is rectangle b a scaled copy of rectangle a

Rectangles are similar figures, thus if scaled copies of each other then the ratios of corresponding sides must be equal
compare ratios of lengths and widths
rectangles A and B
k = = ← ratio of lengths
k = = ← ratio of widths
scale factors are equivalent, hence rectangle A is a scaled copy of B
rectangles C and B
k = = ← ratio of lengths
k = = ← ratio of width
scale factors (k ) are not equal, hence C is not a scaled copy of B
rectangles A and C
k = = ← ratio of lengths
k = ← ratio of widths
the scale factors are not equal hence A is not a scaled copy of C