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:

   $$2B = 10 \implies B = \frac{10}{2} = 5$$

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

   $$5 + 2F = 10$$

   Subtract 5 from both sides:

   $$2F = 5 \implies F = \frac{5}{2} = 2.5$$

---

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.