If you would like to find the number, you can calculate this using the following steps:
n = ? ... a number
the difference of six times a number and 7 is -49
6 * n - 7 = - 49
6 * n = - 49 + 7
6 * n = - 42
n = - 42 / 6
n = - 7
The correct result would be - 7.