so, let's begin with the second one, since it's a passive circuit (resistors, caps and coils are passive components, op amps, transistors and tubes are active components, and diodes are in a kind of active/passive twilight zone).
start by reducing the circuit to a single voltage and resistance:
first we solve for the 40 ohm resistor in parallel with the resistor string. 40||150=31.5 ohms or 1/((1/40)+(1/150))
then we solve the first string using the parallel combination R=20+31.5+20=71.5 ohms
next we need to find the total current 60/71.5=839mA
then we work back towards the load to find the current and voltage at the load:
next we want the voltage across the parallel string 0.839*31.5= 26.43V
next we want the current through the second string 26.43/150=176mA
and the voltage across the load is: 0.176*100=17.6V
that's how you work with circuits like that, first you simplify to a single voltage source and resistor, then work back to find the current, then the voltage at the load.
usually you spend a lot of time in basic electronics class working with problems like this one before moving on to other passive components and then active components. there are two basic "tools" used in circuit analysis, Thevenin's theorem, where you reduce a complex network to a voltage source and single resistance, and Norton's theorem, where you reduce the network to a current source and a resistor. it takes a bit of logical thinking and math to do this well, which is why so much time is spent teaching these methods. if you were to break down the analysis above, you would see application of both Tevenin's and Norton's theorems for various steps in the analysis, because sometimes i used a voltage source to find the answer to a step, then switched over and then used a current source to find an answer.