Question

A bag contains 2 steel balls and 5 brass balls. The total weight is 13 pounds. If 2 steel balls are added and 2 brass balls are removed, the weight decreases to 12 pounds how much does each kind of ball weigh?
A. Steel: 4 pounds;brass:1pound
B. steel:1.5 pounds;brass:2 pounds
C.steel:0.75 pounds;brass:3pounds
D.steel:3 pounds;brass:4 pounds

Answer 1

Let \(s\) and \(b\) represent the weights of the steel and brass balls, respectively. Then you have
\[\begin{cases}
2s+5b=13\\
4s+3b=12
\end{cases}\]
Initially, you have 2 steel and 5 brass which weigh 13 pounds. Then you add 2 steel and take out 2 brass, and the weight drops by a pound.

Solve the system.