If triangles ABC and XYZ are similar, what is the length of side b?

Length of side b = 12

By doing 15 / 10, we can find how much the right triangle has been reduced compared to the left triangle. So, it’s been reduced by 0.5

Because we’re trying to find side b which is on the larger (left) triangle, we do 8 x 1.5 which is 12