A bar model can be used to a subtraction problem by showing how much of it your actually losing or winning so subtract the totals and you have gotten your answer.
19
If she has already watched 1.5 hours and she can only watch 5 hours per week, then we have the inequality:
1.5 + T ≤ 5
where T is is the number of hours she can watch more before reaching her limit
20
If he needs 100 points, already has 40 and earns 2 for every movie, we have the inequality:
40 + 2m ≥ 100
where m is the number of movies he needs to watch
21
We can have the equation:
x + 1 = x + 2 - 1
This would result to:
x + 1 = x + 1
which have the same terms on both sides.
Further, the equation would be:
0 = 0