When it comes to percentages with tips and taxes they are basically asking, in this case, "What is 6% of 45?" and "What is 20% of 45?".
To find the percentages, you need to convert the percentages to decimals.
6% = 0.06
20% = 0.2
Now that we have our decimals, we must multiply them by 45.
0.06 × 45 = 2.7
0.2 × 45 = 9
Now, add 9 and 2.7 to 45.
45 + 9 + 2.7 = 51.7
The total cost for their meal is $51.70.
I hope this helped. :)