Answer
Step-by-step explanation:
As the three resistors are connected in series, the expression to be used for the
calculation of RT equivalent resistance
is:
RT = R1 + R2 + R3
We replace the data of the statement in the previous expression and it remains:
5 10 15 RT + R1 + R2 + R3 + +
We perform the mathematical operations that lead us to the result we are looking for:
RT - 30Ω