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05-16-2006, 08:49 PM
Together, a baseball and a football weigh 1.25 pounds, the baseball and a soccer ball weigh 1.35 pounds, and the football and the soccer ball weigh 1.9 pounds. How much does each of the balls weigh?

stapel
05-16-2006, 09:59 PM
Hint: How much would two baseballs, a football, and a soccer ball weigh? So how much would just the two baseballs weigh?

Eliz.
__________

Mrspi
05-16-2006, 11:33 PM
Together, a baseball and a football weigh 1.25 pounds, the baseball and a soccer ball weigh 1.35 pounds, and the football and the soccer ball weigh 1.9 pounds. How much does each of the balls weigh?

I guess I would approach the problem this way:

let b = weight of one baseball
let f = weight of one football
let s = weight of one soccer ball

Then, from the statements in the problem, we have this:
b + f = 1.25
b + s = 1.35
f + s = 1.9

You can solve the first equation for f:
b + f = 1.25
f = 1.25 - b

You can solve the second equation for s:
b + s = 1.35
s = 1.35 - b

Now, substitute the expressions you have for f and s into the third equation:
f + s = 1.9
(1.25 - b) + (1.35 - b) = 1.9

Can you finish it now?

soroban
05-16-2006, 11:40 PM
Hello, c4duffy!

Together, a baseball and a football weigh 1.25 pounds,
the baseball and a soccer ball weigh 1.35 pounds,
and the football and the soccer ball weigh 1.9 pounds.
How much does each of the balls weigh?
We have: \,\begin{array}{ccc}B\,+\,F\;\;\;\;=\;1.25 \\ B\,\;\;\;+\,S\;=\;1.35 \\ \;\;\;F\,+\,S\;=\;1.90\end{array}

Solve the system of equations:

\;\;\;B\,=\,0.35,\;F\,=\,0.90,\;S\,=\,1.00