Comments on: Can You Do Fourth Grade Math?

By: Jay

Jay — Mon, 27 Mar 2006 03:38:19 +0000

Yes, everybody got the answer right. Dante set the problem up right in the first comment.

To solve, take the first equation and solve for x.

x - b = 12.

Thus, x = 12 + b.

Now, plug this value in for x in the second equation.

b = 4(12 + b)
b = 48 + 4b
-48 = 3b
b = -16

Bella’s brother is -16 years old.

Now take b and plug it back into either equation and solve for x to get Bella’s age.

-16 = 4x
x = -4

So Bella is -4 years old.

Dante — Sun, 26 Mar 2006 08:16:41 +0000

Wait, the answers are negative numbers? I don’t think I learned negative numbers until about 6th or 7th grade.

Joe St — Sun, 26 Mar 2006 04:48:16 +0000

If they start giving out negative years, I’d like to apply for a few, please.

keiths — Sat, 25 Mar 2006 22:20:03 +0000

By my calculations, Bella will be born in 2010, and her brother will be born in 2022. Now that’s what I call family planning.

Dante — Sat, 25 Mar 2006 06:50:01 +0000

What state is this again? Texas?

I didn’t get it, but it can be expressed algebraically as:

x -b = 12 b = 4x

*whoosh* Not a clue.