The answer would be 85.
First, you start by distributing your six in the parentheses. For instance, 6 x j equals 6j and 6 x -87 equals -522. Once you get this, you should have -12 = 6j - 522. You then have to add 522 on both sides to cancel out the -522. This will then give you 510 = 6j. You then divide six on both sides and j will equal to 85.