In a kite, two opposite angles are equal. In this case, angle K is equal to angle M. And since the angles in a kite add up to 360 in a quadrilateral, we can get the equation,
2x+48+70=360
where x is angle K or angle M
and so solve for x
2x+118=360
2x=242
x=121
Angle K = 121 degrees
Hope this helps.