Idon't know what the answer is because my calculator won't calculate it out

Our goal is to collect email addresses from 60% of customers who purchase a product." so that means if i talk to 95 customers, i need to persuade to provide an email address?

Determine the common ratio and find the next three terms of the geometric sequence. 10, 2, 0.4, a. 0.2; -0.4, -2, -10 c. 0.02; 0.08, 0.016, 0.0032 b. 0.02; -0.4, -2, -10 d. 0.2; 0.08, 0.016, 0.0032 select the best answer from the choices provided a b c d

Idon't get undoing if its pass adding and subtracting so can someone ? x-2 over 5 = 18