How to find the power delivered to the load?
Don't worry about power just yet. You've got the total resistance right, so you can figure the total current. Now you just have to figure out where the current goes.

Hint: look at where the current splits between R2 and R7. Figure out how much current goes to R7. Then look at point c and figure out the ratio of currents there. Finally, apply the fraction to the total, and apply that to R4.