Answer:
A [tex]x=4[/tex]
Step-by-step explanation:
Perimeter = the sum of all side lengths
Perimeter = [tex](x-3)+2x+6[/tex]
Perimeter = 15 (in this case)
so...
[tex](x-3)+2x+6=15[/tex]
And we're trying to solve for x.
Step 1. Subtract 6 to both sides
[tex](x-3)+2x=9[/tex]
Step 2. Add 3 to both sides
[tex]x+2x=12[/tex]
Step 3. Combine like terms
[tex]3x=12[/tex]
Step 4. Solve for x
[tex]x=\frac{12}{3}[/tex]
[tex]x=4[/tex]
