Guys this question is about system of equation word problem

assist me !

Let f and s represent the weights of the first and second objects, respectively.
.. f - s = 200 . . . . . . . . the first is 200 lb heavier than the second
.. s = (1/3)f . . . . . . . . . . the second was 1/3 the weight of the first

In augmented matrix form, the equations can be written
.. f - s = 200
.. f - 3s = 0

The solution is
.. f = 300
.. s = 100
Their total weight is 400 lb, not enough to kill Mr. Boddy. The physics-loving professor is apparently innocent.