Automation with a growth rate

I need to have the value in collumn U begin to grow at 3% once there is a positive value in collumn B. I want the intial value in collumn U to come from the input field "Net Income Need" on the second page. Thanks

This is the sum I am using in collumn U =SUM(U10*3%)+U10, I want something like IF(B3>0,SUM(U10*3%)+U10,0) , but having it take the initial value from the second page input