Three charges,
q1 = +1.98 10-9 C,
q1 = +1.98 10-9 C,
q2 = -3.15 10-9 C,
and
q3 = +1.06 10-9 C,
are located on the x-axis at
x1 = 0, x2 = 10.0 cm,
and
x3 = 20.0 cm.
Find the resultant force on q3.