Answer
$(4,7)$ is a solution,
$(3,4)$ is not a solution,
$(0,-4)$ is not a solution.
Work Step by Step
An ordered pair (a,b) is a solution of an equation in x and y if,
substituting a for x and b for y,
we obtain an equation that holds true.
Another way of stating this is that (a,b) satisfies the equation.
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$(x,y)=(4,7)$
$(4)-4=0 \qquad$ .... true, a solution
$(x,y)=(3,4)$
$(3)-4=0 \qquad$ .... false, not a solution
$(x,y)=(0,-4)$
$(0)-4=0 \qquad$ .... false, not a solution
