Question

Ping is buying a sandwich for $5.95 and a bottle of juice for $1.75. He is going to pay with a $10 bill.

Answer 1

If  Ping buys a sandwich and bottle of juice at that price , his total would be $7.70 in a world without tax. So 10.00-7.70 and his change would be $2.30 :) 
But without plugging this into a calculator round the numbers up , $6+$2=$8 leaving him with approximately $2 in change.

You did this correctly :) I'm proud

Answer 2

Yes, u did it correctly.

estimate : 10 - (6 + 2) = 10 - 8 = 2
exact : 10 - (5.95 + 1.75) = 10 - 7.70 = 2.30