Answer:
20 minutes
Explanation:
The question can be shown like so, 1.5+0.6x
Since the total charge was 13.5, you can write an equation
13.5=1.5+0.6x
Simplify using property of subtraction
13.5 - 1.5= 1.5 - 1.5 + 0.6x
12 = 0.6x
Simplify using property of division
12/0.6= 0.6x/0.6
x=20