Question: Can you guide me through solving this problem: Rory orders 2 subs for $7.50 each, 2 bags of chips for $1.50 each and 2 cookies for $1.00 each for delivery.  There’s a 20% delivery fee added at check out and she wants to add a $5.00 tip.  What will her delivery order cost?
Answer: 
2 subs are $7.50 each so that’s 2*7.50 = $15.00
2 bags of chips are $1.50 each so that’s 2*1.50 = $3.00
2 cookies are $1.00 each so that’s 2*1 = $2.00
Her delivery order will be 15+3+2= $20.00
There’s a 20% delivery fee on the $20.00 which adds .20*20 = $4.00 to her bill
The delivery order is $20.00, there’s a $4.00 delivery fee and she adds a $5.00 tip for a total of 20+4+5 = $29.00