V1 +V2 +V3 = 10v so V3 = 10-5 = 5v
The equation for a voltage divider which is just a series circuit is V1 = VR1 / (R1 +R2 +R3); V2 = VR2 / (R1 +R2 +R3); V3 = VR3 / (R1+R2+R3). Using your now known values of V1, V2 and V3 you can substitute into the above formulas to find that R2 = 4R1 and R3 = 5R1.
Let R1 = 50 ohms then R2 = 200 ohms and R3 = 250 ohms. This can be done with two of your 50 ohm resistors and two of your 200 ohm resistors since 200 +50 would give you the R3 value.
The total resistance is R1 + R2 + R3 or 500 ohms. Thus the total current I is 10v / 500 ohms or 1/50 amp.
The voltage across R1 is IR1 or (1/50)(50) = 1v
The voltage across R2 is IR2 or (1/50)(200) = 4v
The voltage across R3 is IR3 or (1/50)(250) = 5v