Question 141359This question is from textbook Prentice hall algebra 1
: How do I solve using a system of two linear equations in two variables?
Barry is 8 years older than his sister. In 3 years, he will be twice as old as she will be then. How old is each now?
This question is from textbook Prentice hall algebra 1
Found 2 solutions by nabla, ankor@dixie-net.com:
Answer by nabla(475)   (Show Source):
You can put this solution on YOUR website! This would be the system of equations I would come up with:
b=s+8 read as b is s plus 8
b+3=2(s+3) read as 3 more than b is 2 times 3 more than s
Solve by substituting the solution for b in the first equation into the second.
That is done as follows:
s+8+3=2s+6
5=s
This means that Barry's sister is 5 years old.
Now, to find Barry's age we plug in s=5 into the first equation:
b=5+8=13. Barry is 13.
Let's check this:
Is Barry currently 8 years older than his sister who is 5? Yes, 5+8=13.
In 3 years, will Barry be twice as old as his sister? 5+3=8; 13+3=16; 2(8)=16; Yes.
Answer by ankor@dixie-net.com(22740)  (Show Source):
You can put this solution on YOUR website! How do I solve using a system of two linear equations in two variables?
Barry is 8 years older than his sister. In 3 years, he will be twice as old as she will be then. How old is each now?
:
Let x = B's age now
Let y = S's age now
:
Write an equation for the statement,"Barry is 8 years older than his sister."
x = y + 8
or
x - y = 8
:
The same for this statement," In 3 years, he will be twice as old as she will be then.
(x+3) = 2(y+3)
x + 3 = 2y + 6
x = 2y + 6 - 3
x = 2y + 3
x - 2y = 3
:
The system, two equations two variables
x - y = 8
x - 2y = 3
------------ subtracting eliminates x
0 + y = 5 yrs is sister's age now
:
I'll let you find Barry's age
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