Maths question!! please help!!!!!

Robert and Miriam need chocolates as prizes for a quiz: they decide on four bags of Revels, five Mars Bars and five Twix Bars. However, they don’t coordinate their shopping! Robert buys three bags of Revels, two Mars Bars and four Twix Bars for £5.85; Miriam separately purchases two bags of Revels, four Mars Bars and three Twix Bars for £5.60. They return the excess goodies to the shop, receiving £2.60 back. How much does each item cost?

you can say that mars is M, Twix is T and Revel is R
Robert buys 3xR+2xM+4xT for 5.85 (=5.85)
Miriam buys 2xR+4M+3T=5.60
they have 5xR;6M and 7T which means that they give back 1xR+1xM+2T=2.60

now you have 3 linear equotations and you can start solving

3xR+2xM+4xT=5.85 /*2
2xR+4M+3T=5.60 /*-3
and sum these two= -8M-T=11.70-16.8

2xR+4M+3T=5.60
1xR+1xM+2T=2.60

2*(2.60-M-2T)+4M+3T=5.60
+2M-T=0.40

-8M-T=11.70-16.8
-2M+T=-0.40(multiplied by -1)
sum of these two = -10M=-5.5
Mars costs 55p

you put this into -2M+T=-0.40 you'll get Twix=60p
and finally from 1xR+1xM+2T=2.60 you'll get R = 85p

Let X be price of Revels
Let Y be price of Mars
Let Z be price of Twix

3X + 2Y + 4Z = 5.85

2X + 4Y + 3Z = 5.60

They return 1 bag of Revels, 1 Bag of Mars, and 2 bags of Twix.

X + Y + 2Z = 2.60

Now just solve this system! :)

R = Revel bag
M = Mars bar
T = Twix

3R+2M+4T = £5.85
2R+4M+3T = £2.60

Simultaneous equations

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