1. **State the problem:** Solve the simultaneous equations for the variables involved.
2. **General approach:** To solve simultaneous equations, we use substitution or elimination methods.
3. **Example:** Suppose the system is:
$$\begin{cases} ax + by = c \\ dx + ey = f \end{cases}$$
4. **Step 1: Solve one equation for one variable.** For example, solve the first equation for $x$:
$$x = \frac{c - by}{a}$$
5. **Step 2: Substitute into the second equation:**
$$d\left(\frac{c - by}{a}\right) + ey = f$$
6. **Step 3: Multiply both sides by $a$ to clear the denominator:**
$$\cancel{a} \cdot d \left(\frac{c - by}{\cancel{a}}\right) + aey = af$$
$$dc - dby + aey = af$$
7. **Step 4: Group terms with $y$ and solve for $y$:**
$$(-db + ae) y = af - dc$$
$$y = \frac{af - dc}{-db + ae}$$
8. **Step 5: Substitute $y$ back into the expression for $x$:**
$$x = \frac{c - b \left(\frac{af - dc}{-db + ae}\right)}{a}$$
9. **Step 6: Simplify the expression for $x$ to find its value.**
This method applies to any two linear simultaneous equations.
**Final answer:** The solution $(x,y)$ is given by
$$x = \frac{c - b \left(\frac{af - dc}{-db + ae}\right)}{a}, \quad y = \frac{af - dc}{-db + ae}$$
Simultaneous Equations A7860E
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