resize - How to increase size of /boot partition using gparted

please help me here
i am always getting messages saying no free space available in boot partition.

output of ls -alh /boot

total 79M
drwxr-xr-x 4 root root 1.0K Sep 7 20:53 .
drwxr-xr-x 23 root root 4.0K Sep 5 18:38 ..
-rw-r--r-- 1 root root 1.2M May 8 16:14 abi-3.16.0-38-generic
-rw-r--r-- 1 root root 1.3M Aug 17 12:10 abi-4.1.6-040106-generic
-rw-r--r-- 1 root root 168K May 8 16:14 config-3.16.0-38-generic
-rw-r--r-- 1 root root 177K Aug 17 12:10 config-4.1.6-040106-generic
drwxr-xr-x 5 root root 1.0K Sep 5 14:23 grub
-rw-r--r-- 1 root root 28M Aug 22 22:49 initrd.img-3.16.0-38-generic
-rw-r--r-- 1 root root 28M Aug 24 00:35 initrd.img-4.1.6-040106-generic
drwx------ 2 root root 12K Aug 12 12:52 lost+found
-rw-r--r-- 1 root root 173K Mar 12 2014 memtest86+.bin
-rw-r--r-- 1 root root 174K Mar 12 2014 memtest86+.elf
-rw-r--r-- 1 root root 175K Mar 12 2014 memtest86+_multiboot.bin
-rw------- 1 root root 3.4M May 8 16:14 System.map-3.16.0-38-generic
-rw------- 1 root root 3.6M Aug 17 12:10 System.map-4.1.6-040106-generic
-rw-r--r-- 1 root root 6.1M Jun 28 01:15 vmlinuz-3.16.0-38-generic
-rw------- 1 root root 6.4M Aug 17 12:10 vmlinuz-4.1.6-040106-generic

output of sudo parted -l

Model: ATA ST9500325AS (scsi)
Disk /dev/sda: 500GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Number  Start   End    Size    Type      File system     Flags
 1      1049kB  106MB  105MB   primary   ntfs            hidden
 2      106MB   140GB  140GB   primary   ntfs            boot
 3      140GB   471GB  331GB   primary   ntfs
 4      471GB   500GB  29.5GB  extended                  lba
 5      471GB   493GB  22.0GB  logical   ext4
 6      493GB   499GB  6536MB  logical   linux-swap(v1)
 7      499GB   500GB  910MB   logical   ext4

@Pilot6

You need to boot from Ubuntu LiveUSB first.

Your sda5, sda6 and sda7 partitions are inside the extended sda4 partition.

You will need to extend sda4, then move sda5 and sda6 left, then extend sda7.

You will also need to re-install grub, because start sector of your /boot partition will change. It can be done from LiveUSB by

sudo mount /dev/sda5 /mnt
sudo mount /dev/sda7 /mnt/boot
sudo chroot /mnt
sudo grub-install /dev/sda
exit