JMK’s angle is part of the right angle of JMN. The measurements there is 28°. A right angle is 90° so subtract 90 and 28 to get your angle measurement of JMK.
A small hint for the STR one is the fact that the straight lines are 180°. So Look at the line RTS. RTS is 180° by adding both the measurement of STR and STP. Simply subtract 180° with 118 to get STR.
