$$\\\frac{4}{7}-(-3)\\
=\frac{4}{7}--3$$
Now thinking just about + and - signs
If two signs are so close together that you can put a circle around them without anything else getting in the way THEN if the signs are different then it will be a - and if the signs are the same then it will be a +
$$Here $--$ is replaced with a $+$$$
You should be able to finish it now :)
$$\\\frac{4}{7}-(-3)\\
=\frac{4}{7}--3$$
Now thinking just about + and - signs
If two signs are so close together that you can put a circle around them without anything else getting in the way THEN if the signs are different then it will be a - and if the signs are the same then it will be a +
$$Here $--$ is replaced with a $+$$$
You should be able to finish it now :)