



 
Hi Steve, Let me illustrate with a different expression, $7x  4y = 7.$ You are then given a pair of numbers, say $(5, 7)$ and asked if this pair of numbers is a solution of $7x  4y = 7.$ In your question, for the par of numbers $(3, 2)$ it doesn't say which is $x$ and which is $y$ but it is conventional to write $x$ first and then $y$ so I am going to word my problem more carefully.
To solve this I substitute $x = 5$ and $y = 7$ into the left side of the equation and see if the value I obtain is equal to the right side. Substitution gives \[7x  4y = 7 \times 5  4 \times 7 = 35  28 = 7.\] This is equal to the right side so $(x, y) = (5, 7)$ is a solution to $7x  4y = 7.$ Let's try another pair of numbers.
Substitution this time yields \[7x  4y = 7 \times 6  4 \times 1 = 42  4 = 38.\] The result is not equal to the right side of the equation $7x  4y = 7$ and hence $(x, y) = (6, 1)$ is not a solution to the equation in two variables $7x  4y = 7.$ I hope this helps,  


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