$\"\"$

The word “sum” indicates the symbol “+”.

The word “is” indicates the symbol “=”

Let n represents the number.

Rewrite the sentence into equation,

$\"\"$ $\"\"$

The equation is $\"\"$ .

$\"\"$

According to addition property of equality: if a = b, then a + c = b + c.

$\"\"$ (Add 43 to each side)

$\"\"$ (Additive inverse property: $\"\"$ )

$\"\"$ (Add: $\"\"$ )

$\"\"$

Check:

To check the solution, substitute $\"\"$ in original equation.

$\"\"$

$\"\"$ (Subtract: $\"\"$ )

Compare the values, the equation is true. The solution is $\"\"$ .

$\"\"$

The number is 145.