Three resistors of 15.0 ohms, 30.0 ohms, and 60.0 ohms respectively are connected in parallel to an applied potential difference of 90 volts. (a) draw the circuit (b) calculate the equivalent resistance (c) calculate the total current through the circuit (d) calculate the power dissipated in the 60 ohm resistor

A).  The drawing looks like a ladder with 4 rungs.
One rung is a 90-volt battery.
The other 3 rungs are the 3 resistors.

b).  The equivalent resistance is the reciprocal of (1/15 + 1/30 + 1/60).
That's the reciprocal of  7/60, or about 8.571... ohms. 

c).  I = V/R = 90 / 8.571...  =  10.5 Amperes.

d).  The 60-ohm resistor is connected directly across the battery.

Power = V²/R = (90²) / 60  =  135 watts.  Better COOL that baby !