Your height: 4'10" to 5'2" approximatly (?).
Frame size = 18in/46cm
Comments:
Mountain Bikes: they are sturdy and designed to go everywhere including off-road. Good for rough riding. In general heavy and with deep thread tires slow on paved roads. Not good city bikes unless narrower and slick tires are installed.
15 speed: perfect to go everywhere including going up very steep hills. There are 3 front chain rings and 5 rear gears. - Derailleur: Shimano Tourney
Tires 26 x 1.75: medium width tires with small thread, for comfort on asphalt and occasional off-road.