Hi, i am having a little bit of difficulties with ratios and proportions and would really appreciate if someone could help me understand this problem.

Solve x : 6/8 = 9/x+7

Alright so here's what i would do :

8 * 9 = 72 / 6.

72 divided by 6 = 12

12 + 7 = 19.

x = 19.

Apparently, this is wrong. The correct answer is :

12 - 7 = 5.

x = 5.

My question is, why exactly do you have to subtract 7 instead of adding it?