Current analysis with 2 voltage sources

circuit analysiscurrentvoltage-source

I am not able to solve this question , I initially thought that in order to find the current of this series circuit it would be Vtotal / RTotal , however I am not getting the correct answer with this method. There must be another factor I'm not aware of when it comes to dealing with 2 voltage sources. Can anyone shed any light on why I'm not getting the correct answer ?
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Best Answer

recognize that the two voltage sources are not acting in the same direction.so you need find the resultant voltage in that circuit which is 50v-12.5v=37.5V and use the formula you wrote above to find I=37.5v/Rtotal = 37.5/15 = 2.5A. The voltage across the 7 ohm resistor is gotten by applying ohms law: v=IR = (2.5)(7)= 17.5v