For the first day, 
beg_hr = beg_tip = 0;
end_hr = beg_hr + (hrs for first day from data);
end_tip = beg_tip + (tips for first day from data). 

For every day afterwards:
beg_hr(current) = end_hr(previous day);
beg_tip(current) = end_tip(previous day);

end_hr(current) = beg_hr(current) + hrs(current)
end_tip(current) = beg_tip(current) + tips(current)

This pattern should continue until last day is reached.