$\"\"$

\

The values are $\"\"$ .

\

Apply nth term of the arithmetic sequence formula: $\"\"$ .

\

$\"\"$ (Substitute $\"\"$ )

\

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

\

$\"\"$ (Multiply: $\"\"$ )

\

Apply subtraction property of equality: a = b then $\"\"$ .

\

$\"\"$ (Subtract 75 from each side)

\

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

\

Apply sum of an arithmetic series formula: $\"\"$ .

\

$\"\"$ (Substitute $\"\"$ )

\

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

\

$\"\"$ (Multiply: $\"\"$ )

\

$\"\"$ (Divide: $\"\"$ ) $\"\"$

\

The value of $\"\"$ .