Max Value
1. **State the problem:** We want to find the maximum value of the function $$z = 4x + 3y$$ subject to the constraints:
$$x \geq 4$$
$$y \geq 3$$
$$7x + 6y \leq 88$$
2. **Understand the constraints:** These inequalities define a feasible region on the xy-plane:
- $$x \geq 4$$ is the region to the right of the vertical line $$x=4$$.
- $$y \geq 3$$ is the region above the horizontal line $$y=3$$.
- $$7x + 6y \leq 88$$ is the region below or on the line with intercepts $$x=\frac{88}{7} \approx 12.57$$ and $$y=\frac{88}{6} \approx 14.67$$.
3. **Find the vertices of the feasible region:** The maximum of a linear function over a polygonal region occurs at a vertex (corner point).
- Vertex A: Intersection of $$x=4$$ and $$y=3$$ is $$A=(4,3)$$.
- Vertex B: Intersection of $$x=4$$ and $$7x + 6y = 88$$:
Substitute $$x=4$$:
$$7(4) + 6y = 88 \Rightarrow 28 + 6y = 88 \Rightarrow 6y = 60 \Rightarrow y = 10$$
So $$B = (4,10)$$.
- Vertex C: Intersection of $$y=3$$ and $$7x + 6y = 88$$:
Substitute $$y=3$$:
$$7x + 6(3) = 88 \Rightarrow 7x + 18 = 88 \Rightarrow 7x = 70 \Rightarrow x = 10$$
So $$C = (10,3)$$.
4. **Evaluate the objective function $$z=4x+3y$$ at each vertex:**
- At $$A=(4,3)$$:
$$z = 4(4) + 3(3) = 16 + 9 = 25$$
- At $$B=(4,10)$$:
$$z = 4(4) + 3(10) = 16 + 30 = 46$$
- At $$C=(10,3)$$:
$$z = 4(10) + 3(3) = 40 + 9 = 49$$
5. **Determine the maximum value:** Among the values 25, 46, and 49, the maximum is $$49$$ at point $$C=(10,3)$$.
**Final answer:** The maximum value of $$z = 4x + 3y$$ subject to the constraints is $$\boxed{49}$$ at $$x=10$$ and $$y=3$$.