Step 1: Assign variables

 

Step 1: Assign variables

• Let D = value of the drink (cup with straw)
• Let B = value of the burger
• Let F = value of the fries (double pack of fries)

---

Step 2: Write equations from the image

1. D + D + D = 30
   This simplifies to:
   $3D=30$
   So,

   $$D=\frac{30}{3}=10$$

2. D + B + B = 20
   Substitute $D=10$:

   $$10+2B=20$$

   Subtract 10 both sides:

   $$2B=10⟹B=\frac{10}{2}=5$$

3. B + F + F = 10
   Substitute $B=5$:

   $$5+2F=10$$

   Subtract 5 from both sides:

   $$2F=5⟹F=\frac{5}{2}=2.5$$

---

Step 3: Solve the last equation

4. B + F × D = ?
   Pay attention to the order of operations: multiplication comes before addition.

   Substitute $B=5$, $F=2.5$, and $D=10$:

   $$5+2.5\times 10=5+25=30$$

---

Answer: 30

---

Explanation with details:

• Each drink is worth 10.
• Each burger is worth 5.
• Each pack of fries is worth 2.5.
• The final equation uses multiplication and addition. First multiply fries (2.5) by the drink (10) to get 25, then add the burger (5) to get 30.