Triangle abc and Def are congruent but different sizes. The original triangle has side values of 2, 6 and 5. Then the shape is dilated by an unknown factor, giving it the side lengths of 4, x, and 10. Looking at the increase in side lengths we see that theres an increase of 2 to 4, or multiplying by 2 and an increase from 5 to 10, or multiplying by to. So now that we know there was a dilation of 2, we multiply 6 by 2 to find 12
