10×15=150.... 5×5=25.... 150-25=125... A. 125
just have to find the area of the whole thing (10×15), then subtract the small square that isnt a part of it. because the lines on the right side are all equal, they are all 5cm. so, 5×5 is the area of that. subtract 25 from 150. that's your answer. hope it helps :)
