Answer:
12 years old.
Step-by-step explanation:
1) 2x+x=18
2) Now solve 2x+x=18
Add alike terms
3x=18
Now divide both sides by 3 (3x/3 and 18/3)
x=6
So Hannah is 6 years old. Her sister must be 12.
First get like things on the same side:
-5/6b - 1/2b= -2/3 - 3/4
Then find equivalent fractions to make the equation easier to solve.
-5/6b - 3/6b= -8/12 - 9/12
Then just add things together and solve.
-8/6b= -17/12
-8b= 6(-17/12)
-8b= -17/2
b= (-17/2)/-8
b= 17/16
You can then plug the answer back into the original question to make sure it is the correct answer.
