$\"\"$

The arithmetic sequence is $\"\"$ .

In the arithmetic sequence $\"\"$ and common difference $\"\"$ .

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

Substitute $\"\"$ , $\"\"$ and $\"\"$ .

$\"\"$

Add 9 to each side.

$\"\"$

Divide each side by 7.

$\"\"$

124 is the 19th term of the arithmetic sequence.