How to create a my own currency formula in a script?

 
Hi everyone

I'm new in Meta trade Scripts. I want to create a script with mutiple currency

Let say, I want to create a scripts with a formula let say A=GBPUSD(sale)+0.01USDJPY(sale) and B=GBPUSD(buy)+0.01USDJPY(buy) and load in template which plot graph A and B with different line color in EURUSD chart .
 
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