Max Profit Books
1. **State the problem:**
Find the number of book gambar ($x$) and book tulis ($y$) to maximize profit given resource constraints.
2. **Define variables:**
Let $x$ = number of buku gambar produced
Let $y$ = number of buku tulis produced
3. **Constraints:**
- Kertas: $5x + 4y \leq 100$
- Perekat: $2x + y \leq 30$
- Non-negativity: $x \geq 0$, $y \geq 0$
4. **Objective function (profit to maximize):**
$$Z = 300x + 200y$$
5. **Method: graphical linear programming with shifting objective line:**
Plot constraints and find feasible region intersections.
- Intersections:
- When $y=0$ in kertas constraint: $5x = 100 \Rightarrow x=20$
- When $x=0$ in kertas constraint: $4y=100 \Rightarrow y=25$
- When $y=0$ in perekat constraint: $2x=30 \Rightarrow x=15$
- When $x=0$ in perekat constraint: $y=30$
- Intersection of constraints:
Solve:
$$5x+4y=100$$
$$2x+y=30$$
Multiply second by 4:
$$8x + 4y =120$$
Subtract first:
$$(8x+4y)-(5x+4y)=120-100 \Rightarrow 3x=20 \Rightarrow x=\frac{20}{3} \approx 6.67$$
Substitute into $2x+y=30$:
$$2(6.67) + y =30 \Rightarrow 13.33 + y=30 \Rightarrow y=16.67$$
6. **Feasible corner points:**
- A$(0,0)$: $Z=0$
- B$(0,25)$: $Z=300(0)+200(25)=5000$
- C$(6.67,16.67)$: $Z=300(6.67)+200(16.67)=2001+3334=5335$
- D$(15,0)$: $Z=300(15)=4500$
7. **Check which gives maximum profit:**
Point C (approx. $(6.67,16.67)$) gives maximum profit $Z=5335$.
8. **Conclusion:**
The company should produce approximately 7 buku gambar and 17 buku tulis to maximize profit with $Z \approx 5335$.