Step 1: Add the price of a muffin to the price of a cup of milk.
Step 2: Multiply that total by 2.
Step 3: Add the tip to the final total for all the items.
Step 4: Subtract the total amount with tip from $20.
1.99+1.50=3,49
3.49 x 2=6.98
6.98+1.40=8.38
20-8.38=$11.62