How do you do system of equations?

Question

Okay....
Christina weighs 17 pounds more than twice her sister Sarah's weight. When both girls stood on the freight scale, the reading was 179 pounds. How much does Christina weigh?

Okay....
Christina weighs 17 pounds more than twice her sister Sarah's weight. When both girls stood on the freight scale, the reading was 179 pounds. How much does Christina weigh?
I need to write a algerbric equation to that problem... I don't understand how to write the system of equation from that problem... If that made any sense at all....

Answer 1

more specific please. There's a lot of types of equations

Answer 2

Let X represent the weight of Christina.
Let Y represent the weight of Sarah.
1) X+Y= 179
2) X-17=2Y
Isolate Y in 1
1) Y=179-X
Sub 1 into 2
2)X-17 = 2(179-X)
X-17 = 358 -2X
3X = 375
X = 125
Sub X = 125 into 1
125+Y = 179
Y = 54

Check
125-17 = 2(54)
108 = 108

Christina's weight is 125 pound.

Answer 3

Christina weight 17lbs more than Sarah. But we don’t know how much Sarah weighs, therefore Sarah’s weight is unknown which makes her the variable (X)

Sarah
X

Christine weight 17lbs more than Sarah, therefore

Christine
17+X

Their total weight is 179. So both of them together weigh 179.

Now you want to add Christina and sarah both
(Sarah) (Christine)
X + X+17= 179
Solve the equation and you get:
2x+17=179
-17 -17
2x =162
2 2
X = 81

Now that x=81, you substitute the x

Sarah weights 81, because she is X
Christina weights 17+x
17+81=98

Answer 4

We see immediately that C = 2S + 17, and C + S = 179. The latter can be expressed as C = 179 - S, which, combined with the first equation, gives 179 - S = 2S + 17, or 162 = 3S. The rest is trivial.

Answer 5

Assuming the equations are linear equations, you can solve this problem via substitution (one variable in terms of another), or, for more complex cases, matrix algebra is the way to go.

Good luck.

Answer 6

Aye, more detail please!