Look at figure B, if you notice the length and breath of the triagle on figure A is put side by side. Meaning the small square in the middle of figure B is 2X2. Since figure B is a square, all sides are equal, therefore, area of figure B is = 4 times of area of figure A plus the small 2x2 square in figure B. Area of figure A is 1/2x8x6=24
Now area of figure B is (24x4)+(2x2)=100cm^2.
Now based on the times table and knowing that figure B is a square, that means a number times itself gives you 100...which is 10x10.
Thus the side of the square in figure B is 10cm. 😊