It’s me again lol you’re questions are simple the formula is given in the triangle
The answer is C 39 hz
Please look at the attached image below for the explanation
Given
Three 7 ohm resistor are in series.
The battery is V=10V
To find
The equivalent resistance
Explanation
When the resistance are in series then the resistance are added to find its equivalent.
Thus the equivalent resistance is:

Conclusion
The equivalent resistance is 21 ohm
Do you want me to translate it?
Answer:
141.152 miles per hour is the speed of the plane in miles per hour
Explanation:
Speed of plane = Total distance travelled/total time taken -
v = D/t
Substituting the given values in the above equation, we get
v = 467/3.3 miles /hour
v = 141.152 miles per hour
141.152 miles per hour is the speed of the plane in miles per hour