Answer:
Perimeter: 16x + 16
Area: 40x + 15
Step-by-step explanation:
[tex]l-\text{length}\\\\w-\text{width}\\\\\text{The formula of a perimeter of a rectangle:}\ P=2(l+w)\\\text{The formula of an area of a rectangle:}\ A=lw\\\\\text{We have}\ l=8x+3\ \text{and}\ w=5.\\\text{Substitute:}\\\\P=2(8x+3+5)\\P=2(8x+8)\qquad\text{use the distributive property:}\ a(b+c)=ab+ac\\P=(2)(8x)+(2)(8)\\\boxed{P=16x+16}\\\\A=(8x+3)(5)\qquad\text{use the distributive property}\\A=(8x)(5)+(3)(5)\\\boxed{A=40x+15}[/tex]
