I need a step by step answer. Please write the final answer in the correct form.

1) Solve by substitution:

x - y = 3

2x + y = -4

17) Purchasing: A clothing manufacturer purchased 60 yd of cotton and 90 yd of wool for a total cost of $1800. Another purchase, at the same prices, included 80 yd of cotton and 20 yd of wool for a total cost of $1000. Find the cost per yard of the cotton and the wool.

Subject | Mathematics |

Due By (Pacific Time) | 05/05/2013 06:54 pm |

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