Which two numbers (not individual digits) should be interchanged to make the given equation correct?
21×5−35+(42÷7)+28=96

Let's test the options using the BODMAS rule to find which interchange makes the LHS equal to 96.
The original equation is:

21×5−35+(42÷7)+28=96
Test Option A: Interchange 28 and 35
The equation becomes:

21×5−28+(42÷7)+35
Solve bracket: 42÷7=6

Solve multiplication: 21×5=105

Substitute back: 105−28+6+35

Combine additions: 105+6+35=146

Subtract: 146−28=118
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=96

Test Option B: Interchange 35 and 42
The equation becomes:

21×5−42+(35÷7)+28
Solve bracket: 35÷7=5

Solve multiplication: 21×5=105

Substitute back: 105−42+5+28

Combine additions: 105+5+28=138

Subtract: 138−42=96

Since LHS=96=RHS, interchanging 35 and 42 makes the equation correct.