15=x+13
EASY. subtract 13 from both sides, and it's (x=2)
You clearly did not study the web site that was given to you. You had posts about every 3 minutes for a half hour, at which time you said you didn't understand the web site. I call BS. You had not had time to spend any time looking at it.
x+11=9
Post it and I will check it.
18
x+11=9
You need to move the 11 to the other side. Since it's a positive number, you need to subtract it from both sides;
x = -2
x-17=-9
x=26
No.
Add 17 to both sides.
Remember, you're trying to get the number to the other side. So you add a negative number to both sides. You subtract a positive number from both sides.
Study this site.
https://www.mathsisfun.com/algebra/equations-solving.html
15=x+13
do i do the 15 or 13