8. CBQ - Science lab equipment

4 m.

A science teacher buys $x$ boxes of wires costing $₹25$ each 10 batteries costing $₹19$ each. A student writes the total cost as:

$25x + 10 + 19$

1. Identify the mistake in the expression.

2. The correct algebraic expression is

3. If $x = 4$, then the total cost is

4. Verify your answer by direct calculation.

Cost of wires $= 25(4) = 100$

Cost of batteries $= 10 \times 19$ $= 190$

Total cost $= ₹100 - 190$ $= ₹-90$
Cost of wires $= 25(4) = 100$

Cost of batteries $= 10 \times 19$ $= 190$

Total cost $= ₹100 + 190$ $= ₹290$
Cost of wires $= 10 \times 19 \times 4$ $= 760$

Cost of batteries $= 25$

Total cost $= ₹760 + 25$ $= ₹785$
Cost of wires $= 25(4) = 100$

Cost of batteries $= 10 + 19$ $= 29$

Total cost $= ₹100 + 29$ $= ₹129$

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