To solve this problem we are going to write Let Statements
Let x = number of people in robotics club
Let x+ 12 = number of people in science club
x + x + 12 = 84
2x + 12 = 84
2x = 72
x = 36
Now let's plug x into the expression for the number of people in science club that was written previously.
(36) + 12 = 36
Therefore, there were 36 people in the science club