Simplify

Correct — B. The expression is printed as an image: 6 × [28 ÷ 84 × {36 × 49 ÷ (6 × 7)}].

Round bracket first: 6 × 7 = 42
Braces, left to right: 36 × 49 = 1764, then 1764 ÷ 42 = 42

Square bracket, left to right: 28 ÷ 84 = 1⁄3, then 1⁄3 × 42 = 14

Last operation: 6 × 14 = 84 → option (b)

Why the others are wrong

• (a)
  94 — 94 would need the square bracket to hold 15.67, since the final step multiplies by 6. Worked left to right the bracket is exactly 14.
• (c)
  64 — 64 needs a bracket value of 10.67. It is the kind of number you reach by dividing 28 by 84 and then forgetting to bring in the 42.
• (d)
  74 — 74 is not even a multiple of 6, so it cannot survive a final multiplication by 6 with a whole-number bracket.

Two rules settle this expression, and neither is about which symbol looks stronger.

Brackets resolve from the inside out — round, then curly, then square. So (6 × 7) goes first, then the braces around it, then the square bracket.

Within one bracket, × and ÷ share a single precedence level and are worked strictly left to right. That is why 28 ÷ 84 × 42 is (28 ÷ 84) × 42 = 14, and not 28 ÷ (84 × 42).

Key facts

• Brackets are resolved innermost first: ( ) then { } then [ ].
• Multiplication and division sit at the same level of BODMAS and are performed left to right.
• 28 ÷ 84 × 42 = 14, whereas 28 ÷ (84 × 42) is about 0.008 — the same symbols, a different reading.

Common traps

• Multiplying 84 by 42 first because the multiplication sits next to the brace
• Cancelling 28 ÷ 84 to 1⁄3 and then dropping it before the final × 6
• Opening the braces before the round bracket nested inside them

No directly related past PYQ was found.