Calculating node voltages
These are both rather unusual circuits.
 They appear to come from a very old source.
 The diagrams give the impression of possibly being from an analog computer description. 

Is this homework or an assignment?
 I may have though so, but the transistor circuit is probably not sensible in a normal context - it acts as a hard on off switch and the base drive is vastly higher than ususual. 

An OP070 MAY be a variant of an OP07 (eg an OP070000 exists) which is a very very old design (30+ years) op amp that would not usually be used nowadays - so these may be out of an old book.
 Datasheet for OP07. Original was 1983 dated



The 3 diodes - Vout will be the highest of the 3 input voltages less a nonconducting diode drop. Here the +15V is highest so V at pin 3 is 15V - Vds or about 15-0.2 = 14.8V. Depends on diode type. 

With the transistor circuit the transistor is PNP (suggesting a very old diagram source) and Vin and Vcc is negative - which is correct for PNP normal operation.  R5 will pass about 4.5 mA so the transistor will be turned hard on.
 Q1 collector = output node will be almost at ground. The transistor will have some "saturation voltage" but it will be very low in most cases. It is VERY unusual to drive a transistor via a base resistor that is 10x smaller than the collector resistor. This makes the transistor turn on very hard indeed and Vsat will be very low.