Question

done !!

Answer 1

q1 and q2 are your charges (in this case, they're both 4.5 * 10^(-6)
d = distance = 4.5
k = 9.0 *10^9

so

F = k(q1*q2)/d^2 = (9.0 *10^9)(4.5 * 10^(-6))^2 / (4.5)^2

try plugging this into a calculator, be careful with parentheses/exponents

Answer 2

4.5 E -6
And
4.5 * 10^(-6)

Are equivalent