A lunch special involves selling only fish, medium portions of chips, and potato cakes over a luncheon periods from 12 noon to 2:30pm. The portions were priced as follows:
Flake: $6.00
Chips: $4.50
Potato cake: $1
On the first occasion the lunch special was trialled, 255 portions of food were sold. The total takings for the luncheon special were $1067.50. It was known that there were 50 more portions of chips sold than there were pieces of flake.
a) Construct a system of linear simultaneous equations to represent this.

Question

A lunch special involves selling only fish, medium portions of chips, and potato cakes over a luncheon periods from 12 noon to 2:30pm. The portions were priced as follows:
Flake: $6.00
Chips: $4.50
Potato cake: $1 
On the first occasion the lunch special was trialled, 255 portions of food were sold. The total takings for the luncheon special were $1067.50. It was known that there were 50 more portions of chips sold than there were pieces of flake. 
a)	Construct a system of linear simultaneous equations to represent this.

anonymous · Answer

I know two of them will be:
f+c+p = 255  and
6f+4.5c+p = 1067.50 

but im having trouble with the third one?

kainui · Answer

Well it says there were 50 more portions of chips sold than pieces of potato cake (I'm assuming that's what pieces of flake is).

So c=50+p is your last equation. You can rearrange it to looks like this:

0f+c-p=50