Linear equations and matlab

An orange juice company wants to make 1000 litres of new fruit juice blend out of three types of juice: cranberry, pear and apple juice. the three types of juice can be bought sperately from wholesalers at the following prices: cranberry juice cost $5.90 per litre, pear juice costs $2.60 a litre, apple juice $1.00 per litre. The company wants to spend a total of $2000 in purchasing the three types of juice. The only other constraint is that there must be twice as much pear juice as there is cranberry juice in the final blend, since cranberry juice is quite sour.

(a) Write thse constraints as a sytem of linear equations....

(b) use matlab to solve the system of linear equations

so far i have the constraints which i think are correct....they are:

c + p + a = 1000

5.9c + 2.6p + a = 2000

c = 2p or c - 2p = 0

am i correct???? if so..how would i put that into matlab???