The sisters weight is 16 this is because we know that the brother equals 36. Subtract 4 from that 36 to get the problem to 3w=w+32. So we know that 32 is 2/3 of the 3w because there is only 1 w on that side of the problem. That means that 32 has to equal 2w so divide 32 by 2 to find what w equals.
