7th grade math problem

"Highlander-Datsuns are Forever" (jamesbowland)
09/11/2018 at 21:18 • Filed to: None

This actually took me a few minutes to figure out.

DISCUSSION (16)

I like cars: Jim Spanfeller is one ugly motherfucker > Highlander-Datsuns are Forever
09/11/2018 at 21:30

3x + 2y = 32

4x + 3y = 44

Weight the equations as follows to cancel out one variable:

9x + 6y = 96

8x + 6y = 88

And subtract to get x = 8 lbs. Now plug and chug:

3*8 +2y = 32

24 + 2y = 32

2y = 8, so y = 4.

Use the other equation to check:

4*8 + 3*4 = 44

32 + 12 = 44

44 = 44

Now do 2x + y = 2*8 + 4 = 16 + 4 = 20

Quick mafs

That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms > Highlander-Datsuns are Forever
09/11/2018 at 21:32

As a high schooler , I specialized in ‘guess and check’...so this took me about 15 seconds, haha. I’m sure there’s some math way to figure it out the right way, but they never asked you to show you work on the SAT so whatever.

random001 > Highlander-Datsuns are Forever
09/11/2018 at 21:32

5318008

Aremmes > Highlander-Datsuns are Forever
09/11/2018 at 21:34

From the difference between the two lines, one watermelon and one cantaloupe add up to 12 lbs.

w + c = 12
c = 12 - w
3w + 2c = 32
3w + 2(12 - w) = 32
3w + 24 - 2w = 32
w + 24 = 32
w = 32 - 24 = 8

So a watermelon weighs 8 lbs, and a cantaloupe weighs 4 lbs.

TheRealBicycleBuck > Highlander-Datsuns are Forever
09/11/2018 at 21:35

42.

It’s the answer to life, the universe, and everything.

facw > Highlander-Datsuns are Forever
09/11/2018 at 21:38

I can still do math (I think)!

3x + 2y = 32

y = (32-3x)/2

Plugging into the other one:

4x + 3(32-3x)/2 = 44

8 x + 96 - 9x = 88

-x = -8

x = 8

Plugging back in again:

y = (32 - 3(8))/2

y = 4

So:

2(8)+1(4) = 20 lbs . (hope I didn’t screw that up)

Regardless, I’m annoyed that they say “the two watermelons” instead of just “two watermelons” .

Highlander-Datsuns are Forever > Aremmes
09/11/2018 at 21:43

I didn’t think of it this way but it works.

Khalbali > Aremmes
09/11/2018 at 21:45

Except you don’t need to know what each weighs, just what 2 and 1 weigh, so just subtract 12 and done!

Urambo Tauro > I like cars: Jim Spanfeller is one ugly motherfucker
09/11/2018 at 21:47

Too much maf fo me.

I just subtracted 32 from 44 to get the combined weight of one cantaloupe & one watermelon (12), then subtracted two cantaloupes and two watermelons from 32 to get the weight of the remaining watermelon (8) . 12 - 8 = 4 (one cantaloupe).

ItalianJobR53 - now with added 'MERICA and unreliability > TheRealBicycleBuck
09/11/2018 at 21:50

If I ever get a Miata, the plate would read MX5IS42

I like cars: Jim Spanfeller is one ugly motherfucker > Urambo Tauro
09/11/2018 at 22:01

It’s not about getting the right answer, it’s about the process. Elementary/middle/high school math isn’t about building a useful skill set; it’s about forming mental pathways and reflexes that allow you to approach problems in systematic ways.

AkursedX > Highlander-Datsuns are Forever
09/11/2018 at 22:06

I got the answer easy enough, I just don’t like how it’s worded.

“What is the weight of THE two watermelons and one cantaloupe?”

At no point in the information was a grouping of two and one mentioned. It should have been:

“What is the weight of two watermelons and one cantaloupe?”

Highlander-Datsuns are Forever > AkursedX
09/11/2018 at 22:11

I want to say “weight them and get back to me with the answer, thanks.”