Question

What is the latitude of Zaria lat °xn if the distance between kaduna (30°s) and Zaria is 1625km.

Answer 1

Zaria

11.0855° N, 7.7199° E

Answer 2

This question does not make much sense to me.
Zaria is a city IN Kaduna , Nigeria
perhaps you mean airports?
Zaria airport about 11deg 7 min N and 7 deg 41 min E
Kaduna airport about 10 deg 41 min N and 7 deg 19 min E

IF (and only if) they were at the same Longitude
1.00 nautical mile is a minute (1/60 degrees) of latitude
there are 0.54 nautical miles per kilometer
so
0.54 minutes of latitude = one km
1625 km (0.54 min/km) = 877.5 minutes of arc
877.5 min * 1 deg/60 min = 14.6 degrees of latitude difference


Note, a minute of latitude is a nautical mile north south, but a minute of longitude is NOT a mile east west except at the equator. The lines of constant longitude are a minute of arc per mile only at the equator. Those lines approach each other as you get toward the north and south poles and a minute of longitude arc gets less and less distance until it is zero at the poles.