Note that your /opt partition is not actually a separate partition, but simply a directory in your root partition.
Since you're not using a logical volume manager, what you are really asking is if you can increase the size of your root partition. This would involve moving your entire /home partition, which is fairly large. I'm and old fart and may be out of touch, but generally in my experience, you're not going to be able to move the start of that /home filesystem on sda3 to a later spot on that partition without having to migrate the data there.
The absolute easiest thing to do would be to transfer the /opt data to /home (/home/opt) and simpliy make a symlink to it (rsync -av /opt /home; mv /opt /opt/old; ln -s /home/opt /opt). Not the prettiest, but probably the simplest to accomplish