In ${\mathrm{IF}}_5$, the central atom is iodine, which has $7$ valence electrons. Iodine in this molecule has $5$ bonding pairs and $1$ lone pair. Therefore, the number of lone pairs on the central atom of ${\mathrm{IF}}_5$ is $1$.

In ${\mathrm{IF}}_7$, the central atom is also iodine, which has $7$ valence electrons. Iodine in this molecule has $7$ bond pairs and $0$ lone pairs. Therefore, the number of lone pairs on the central atom of ${\mathrm{IF}}_7$ is $0$.

Therefore, the sum of the number of lone pairs in the central atom of ${\mathrm{IF}}_5$ and ${\mathrm{IF}}_7$ is $1+0=1.$.