Electric Potential Question - Trying to Figure out how to utilize q1 an q2 here!?

Question

Question: A positive charge +q1 is located to the left of a negative charge -q2. On a line passing through the two charges, there are two places where the total potential is zero. The first place is between the charges and is 4.00 cm to the left of the negative charge. The second place is 7.00 cm to the right of the negative charge. (a) What is the distance between the charges? (b) Find q1/q2, the ratio of the magnitudes of the charges.

My Thoughts:
Ok...This might be one of the most confusing questions I've ever encountered in Physics! I drew a diagram, but i had no clue what i was doing. I know the equation V = Kq/r is supposed to be used, but i don't know what to substitute in the problem!!! please show me how you do this problem. appreciate all the help i can get!

Book Answer: I only have part b, which is 3.67

(Note: I will award a best answer - i promise)

Answer 1

hey this is simple

first take x as distance b/w charges

then use equation

kq1/x-4 = kq2/4




i m soory make another equation

kq1/x+7 = kq2/7

now u can find
equate and solve what u want


solution is

x-4/4 = x+7/7

solve u will get x = 56/3

put in equation of charge and get the answer