1. Let's start with an example of Algebra: Solve for $x$ in the equation $2x + 3 = 7$. 2. Use the formula for linear equations: $ax + b = c$ where $a$, $b$, and $c$ are constants. 3. Subtract 3 from both sides: $2x = 7 - 3$ 4. Simplify the right side: $2x = 4$ 5. Divide both sides by 2: $x = \frac{4}{2} = 2$ 6. So, the solution is $x = 2$. 7. Next, an example of Physics: Calculate the force $F$ when mass $m = 5$ kg and acceleration $a = 3$ m/s$^2$. 8. Use Newton's second law: $F = ma$ 9. Substitute values: $F = 5 \times 3$ 10. Calculate: $F = 15$ 11. The force is $15$ Newtons. 12. Finally, an example of Chemistry with math: Calculate moles $n$ from mass $m = 18$ g and molar mass $M = 18$ g/mol. 13. Use the formula: $n = \frac{m}{M}$ 14. Substitute values: $n = \frac{18}{18}$ 15. Calculate: $n = 1$ 16. So, there is 1 mole of substance.