These are similar by the AA similarity postulate. There are two angles that are similar and since we know 2 angles in a triangle, we can determine the third angle. Since all three angles are similar, the triangles are similar.
8.3*4 = 33.2 kg. Hopefully that is correct Since Yi Ting weighs 8.3 and her brother is 4 times heavier you would multiply those two numbers to get the answer.