Finding power absorbed by resistor
You're making this way too complicated.







simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. First step ...

Combine R1 and R2. Now you can work out the voltage across 'R5'. Once you have that you can work out the power in R2 using the formula that relates P, V and R. Do you know it?

Note that the question as written can be solved in one step. Since \$ P = I^2R \$ then if the current goes up by a factor of 16 what happens the power? I would then say that the increment in power is that number minus 1.