So,
Let x represent Joe's weight and y represent Jeff's weight.
"Joe weighs 20 lbs. less than twice Jeff's weight."
x = 2y - 20
"If Jeff would gain 10 lbs., then together they would weigh 250 lbs."
(y + 10) + x = 250
We now have our two open sentences.
x = 2y - 20
(y + 10) + x = 250
Get rid of parentheses.
x = 2y - 20
x + y + 10 = 250
We will use Elimination by Substitution.
2y - 20 + y + 10 = 250
Collect Like Terms.
3y - 10 = 250
Add 10 to both sides.
3y = 260
Divide both sides by 3.

Substitute again.

Multiply.

Subtract.

Check.
"Joe weighs 20 lbs. less than twice Jeff's weight."
Jeff's weight times two is 173 and one-third.
20 lbs. less than that is 153 and one-third lbs. Check.
"If Jeff would gain 10 lbs., then together they would weigh 250 lbs."
86 and two-thirds + 10 = 96 and two-thirds.
96 and two-thirds + 153 and one-third equals 250 lbs. Check.

Answer:
11x+2
Step-by-step explanation:
According to his calculations, b has a 3/10 chance to win
You have the right idea but the endpoint is at the wrong location. Instead, the green dot should go at -1. The shading is to the right. We use a closed filled in circle here (instead of an open hole) to tell the reader "include the endpoint". So -1 is part of the solution set.
In short, the graph consists of a closed filled in circle at -1 with shading to the right. This visually describes all values that are larger than -1, or equal to -1.