Struggling with this one –
Tracey paid £3.10 for 7 jelly snakes and 4 sherbets. Madison paid £2.95 for 4 jelly snakes and 7 sherbets. How much does one jelly snake cost? How much does one sherbet cost?
Over to you.

One Jelly snake costs less than one sherbet.
Are these the fruity jelly snakes or the sour ones?

7*x + 4*y = 3.10
4*x + 7*y = 2.95

solve for y

30p & 25p

First off they both need a slap for eating all that sugar.

1) 7j + 4s = 3.1

2) 4j +7s = 2.95

3) 4j = 2.95-7s

4) j = (2.95-7s)/4

5) 7((2.95-7s)/4) + 4s =3.1 (from 4 and 1)

6) (20.65-49s)/4 + 4s = 3.1

7) 20.65 -49s + 16s = 12.4 (mult both sides by 4)

8 ) 20.65-12.4 = 49s -16s (rearrange)

9) 8.25 = 33s

10) s = 8.25/33 = 0.25

11) j = (2.95-7*0.25)/4 = 0.3 (from 4)

J=jelly baby = 30p, s = sherbert = 25p

Adding and dividing gets two sweets costing 55p.
Then throw that back in for snakes to be 30p and sherbets 25p

7J + 4S = 310
4J + 7S = 295

take one away from the other

3J – 3S = 15

divide by 3

J – S = 5 or J = S + 5

substitute into the top line

7 x (S + 5) + 4S = 310

multiply up the brackets

7S + 35 + 4S = 310

tidy it up

11S + 35 = 310

take away 35 from each side

11S = 275

divide by 11

S = 25

J = S + 5, so must be 30

I dont hold much hope for the health of Madison and Tracey if they are typically allowed to graze their way through sweets like this. What will be the rate of decay on their teeth? Based on their current sweet preferences what is Madison’s predicted life expectancy?

Madison? That’s a name now?

25p

I was quite heartened to see sweets still being used, rather than some modern-paranoia example using pine nuts and organic sprouts.

Next time keep the receipt.

Nine years old? You can do it with equations, but I think it’s a lot easier as a bit of a logic puzzle (but then I always did have an odd approach to maths).

Tracey paid £3.10 for 7 jelly snakes and 4 sherbets. Madison paid £2.95 for 4 jelly snakes and 7 sherberts,

Tracy paid £3.10 for 11 sweets.

Madison paid £2.95 for 11 sweets, a saving of 15p.

An extra 15p gets you three more snakes instead of sherberts, therefore the difference between the two sweets is 5p.

So, if Tracey had all 11 sweets as snakes, it’d cost another 4 x 5p, £3.30.

£3.30 / 11 = 30p each.

Ditto if Madison had all sherberts, it’d £2.75 / 11 = 25p.

Who the hell calls their kid Madison? Some people.

For some reason most of these explanations make me think of this guy:

[video]http://youtu.be/pfa3MHLLSWI[/video]

That’s absolutely fantastic, thanks for that.

Poor old Gerald

You’ve struggled with this for 9 years?
Set em out as per Klunk, multiply top equation by 7, bottom by 4, subtract one from other and solve the result for x. Put x back in one of the original equations to get y.

BODMAS

9 years old? Seriously?

Impressed that IanMunro could work out the price of jelly babies from the info given. Skillz 🙂

Must be bloody big jelly babies.

Also, what the hell is a sherbert? Should Madison be paying for those in dollars?

Thanks for the clip Graham – a great feeling of joy when I realised what he was doing (a bit before Carol did).

30p for a sweet?
Far too xpensive – i’d question that…

DrP