Question 1007287
The difference of two numbers is -1. If twice the first number is added to three times the second number, the result is 13. What are the numbers? 
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Call them x & y
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x - y = -1
2x + 3y = 13
2x - 2y = -2   (1st eqn times 2)
--------------------------------------- Subtract
5y = 15
etc