A piece of wire is cut into two pieces. That means each part would be assigned an unknown variable. Let one part be x and the other part be y.
That means,
[tex]x+y=15\operatorname{cm}[/tex]If the longer part is x, and the longer part is 3cm longer than the shorter part, then we would have the following;
[tex]\begin{gathered} x+y=15 \\ x=y+3 \\ \text{This is because x is 3cm longer,} \\ So\text{ the length of x would be y+3} \end{gathered}[/tex]We can now refine the equation as follow;
[tex]\begin{gathered} \text{Where;} \\ x=y+3 \\ x+y=15 \\ y+3+y=15 \\ 2y+3=15 \\ \text{Subtract 3 from both sides;} \\ 2y+3-3=15-3 \\ 2y=12 \\ \text{Divide both sides by 2;} \\ \frac{2y}{2}=\frac{12}{2} \\ y=6 \\ \text{When;} \\ x+y=15 \\ x+6=15 \\ \text{Subtract 6 from both sides;} \\ x+6-6=15-6 \\ x=9 \end{gathered}[/tex]ANSWER:
The length of the shorter piece of wire is 6cm