Answer:
[tex]x=-\frac{9}{4}[/tex]
Step-by-step explanation:
Step 1: Subtract 21 from both sides
[tex]8x + 21 = 3[/tex]
[tex]8x + 21 - 21 = 3 - 21[/tex]
[tex]8x = -18[/tex]
Step 2: Divide 8 from both sides
[tex]8x = -18[/tex]
[tex]\frac{8x}{8}=-\frac{18}{8}[/tex]
[tex]x=-\frac{9}{4}[/tex]
Answer: [tex]x=-\frac{9}{4}[/tex]