In Acorn's Cafeteria there are no prices up. If Molly is charged £1.80 for 3 Muffins and 2 Hot Chocolates and Megan buys 4 Muffins and 4 Hot Chocolates for £4, what is the individual price for a Muffin and a Hot Chocolate?

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i don't think it is possible to get a negative price but seriously it does give a negative price. I also used calculator to solve the equation but still giving negative price.

Answers

2014-06-13T08:26:17+08:00
Let x be the price of muffins
let y be the price of Hot Chocolates

first get the equation where it cost £1.80

£1.80 = 3x+2y     equation 1

next get the equation where it cost £1.80

£4.00 = 4x+4y     equation 2

multiply equation 1 by 2

2(£1.80 = 3x+2y)
£3.6 = 6x+4y      equation 3

equate 2 and 3
-£3.6  6x + 4y  = - £4.00 4x + 4y
-£3.6  6x + 4y + £4.00 - 4x - 4y
2x + £0.4 = 0
2x/2 = -£0.4/2
x = - £0.2

OMG why is it negetive.

solve for y
substitute the value of x to equation 1
£1.80 = 3x+2y
£1.80 = 3 (-£0.2)+2y
£1.80 = - £.6 + 2 y
2y/2 =  £2.40/2
y =  £1.20

checking:
by equation 1.
£1.80 = 3(-£0.2)+2(£1.20)
£1.80 = £1.80

by equation 2

£4.00 = 4(-£0.2)+4(£1.20)
£4.00 = £4.00

since we got a negative price.
it was sold to Molly and Megan in different prices.
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