Let's x be the Sammi's weight and y Buster's weight.
Then, as Buster and Sammi together weigh 112 pounds, then:
Also, Sammi weighs 8 pounds more than Buster, then:
Now, replace equation (2) into equation (1) and solve for y:
And replace the y-value into equation 2 to find x:
As x=64 and y=56, therefor Sammi weighs 64 pounds and Buster weighs 56 pounds.