What is triangle abc ?

(line segments)

Triangle ABD and ADC are righttriangles so u can use the Pythagorean theorem/triples. the triples are 3/4/5 and 5/12/13. 12 is 4x3, and 15 is 5x3, so BD is 3x3, which is 9. AC is 13, as it is part of the Pythagorean’s triples

the image of (6, 9) under a dilation is (4, 6). the scale factor is

b. 2/3