16.
Wiki User
∙ 6y agoUmmmmm this did not help at all! never using this again!
4x5=20 20x4=80
21 5s
One possibility is 55 + 5*5 = 55 + 25 = 80
(5+5+5) x5 +5 =80. Cancels to: (15) x5 +5 =80 75 +5 =80 80=80
4x5=20 20x4=80 come on I'm in yr7 and i knew that straight away
Rubidium has one 5s electron.
20
7
10
75
90