Is it possible to write the following percentage equation to be human readable?

Question

adjusted premium=current premium+(current premium*(1.35*(1-(1-(1-first rbo%)(1-second rbo%)(1-third rbo%)*(1-fourth rbo%)))-1))

Additional context: I have to write this function in JavaScript but the caveat is that the user will be able to check checkboxes with a fixed percentage associated with it. So the fourth rbo code go as high as 16. I wanted someone with more math skills than myself to help me fundamentally understand why we are subtracting 1 from a percentage (what does that yield, the co-efficient)?

"exerpt from instructions" If 3 or more RBOS chosen, need to add (1-RBO%) as multiplier to formula with first and second RBO%s

Answer 1

Yes: $$ A=C\cdot1.35\cdot(1-r_1)(1-r_2)(1-r_3)(1-r_4) $$

Answer 2

Let adjusted premium be $A$.

Let current premium be $C$.

Let the first RBO be $R_1$, the second RBO be $R_2$, the third RBO be $R_3$, and the fourth RBO be $R_4$.

Thus,

$$A=C+(C\cdot1.35\cdot(1-(1-(1-R_1)(1-R_2)(1-R_3)(1-R_4)))$$$$A=C+(C\cdot1.35\cdot(1-R_1)(1-R_2)(1-R_3)(1-R_4))$$

So finally:

$$A=2C\cdot1.35(1-R_1)(1-R_2)(1-R_3)(1-R_4)$$ $$A=2.7C(1-R_1)(1-R_2)(1-R_3)(1-R_4)$$