This is supposed to be a simple question. However, I forgot a lot of the basics and rules I have to follow. I tried to workout the height based on the area: 0.5 x 3 x h = 30 h = 20 But couldn't figure out the rest. Then I thought about going by ratio (not from knowledge but out of desperation): Ratio of sides: 3:1 Based on which, I assumed that the area of the triangles will follow the same ratio and therefore: Area of big triangle : Area of small triangle = 3:1 We know that the bigger one is 30, so the smaller one has to be 10. Answer: B. I am correct according to the answer key. However, I just pulled that ratio thing out of my a*s. So I need someone who knows about these things to help me out so that I may "learn" instead of make stuff up.