Answer:
Step-by-step explanation:
Remark
The thing to note is that the current is the same through the resistors and the battery.
To accomplish this, the resistors must appear as 1 value to the battery. You can only do that it you add the resistors together.
Resistance
R_total = 3 + 7 + 10 all are in ohms
R_total = 20 ohms
Givens
R = 20
E = 12
I = ?
Formula
I = E/R
Solution
I = 12/20
Answer I = 0,6 amperes.