SOLUTION: I am trying to help my daughter with an algebra review sheet and I can not figure out how to do this problem. a/2 + C = 19 a/4 - 3C = -8 Find a thank you very much, Lydia

Question 8017: I am trying to help my daughter with an algebra review sheet and I can not figure out how to do this problem.
a/2 + C = 19
a/4 - 3C = -8
Find a
thank you very much,
Lydia Waller
Answer by glabow(165) (Show Source): You can put this solution on YOUR website!
Since there are two numbers that are represented by "unknowns" (C and a) you can try to find out what C is and then use it to find a.
The first equation says

[subtracting C from both sides]
[subtracting 19 from both sides]
[multiplying both sides by -1 and rearranging]
This value for C can be put into the second equation

[putting 19-a/2 for C]
[multiplying each term in the group by -3]
[getting a common denominator of 4 for the fractions]
[adding the fractions]
[adding 57 to both sides]
[multiplying both sides by 4]
[dividing both sides by 7]
Now put the value for a in the equation for C

Checking:
28/2 + 5 = 14 + 5 = 9
28/4 - 15 = 7 - 15 = -8

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