The scale factor is 1/3.
To find this scale factor, choose a set of sides to compare lengths. For example, taking the left sides of the triangles, which is 9 and 3. 9 is 3 times bigger than the triangle on the right, so that gives us the scale factor of 1/3.
385=15n+85
385-85=15n
300=15n
300/15=n
20=n
7x+(x-4)(X+5)-5x
7x+(X*2+ 5x-4x-20)-5x
7x+(X*2+ x-20)-5x
X*2+3x-20
I’m pretty sure it should be ,B