Analysis:

5-3=2 is put in brackets first.

Then calculate 2x7= 14.

Extended data

Operating rule

1, additive commutative law: In the addition operation of two numbers, the positions of two addends are interchanged and the sum is unchanged. Letters indicate:

a+b=b+a

2, the law of addition and association: three numbers are added, first add the first two numbers, and then add another addend; Or add the last two numbers first, then add another addend, and the sum remains the same. Letters indicate:

(a+b)+c=a+(b+c)

3. Law of Multiplication and Interchange: In the multiplication operation of multiplying two numbers, the positions of the two multipliers are interchanged and the product remains unchanged. Letters indicate:

a×b=b×a

4. Multiplication and association law: When three numbers are multiplied, the first two numbers are multiplied first, or the last two numbers are multiplied first, and the product remains unchanged. Letters indicate:

(a×b)×c=a×(b×c)