Answer:
1. $67.72
2. It's correct.
Step-by-step explanation:
1.
bill: $68.89
discount: $10
tip: 15%
Calculate the total with the discount.
68.89-10=58.89
Now calculate 15% of that.
Convert 15% to decimal by dividing by 100

Multiply

Add this to the original amount.

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Calculate 20% of 148.25
Convert 20% to decimals by dividing by 100

Multiply
This is how much they will tip.
Add this to the original bill;

His estimate is not reasonable because he would have to be more descriptive in order to have his answer justified
That means you first calculate divide and multiply and at the and plus and minus.
So
12 / 2 + 4 - 2 x 3 =
6 + 4 - 6 = 4
They are not in proportion, since its 6:9 round it down (2:3) so pretend the 6 are apples and the 9 are oranges
Every 2 apples there are 3 oranges
So having 9 apples what is that?
2 x ? = 9
2 x 4.5 = 9
So if you want to keep 2:3 you have you times the oranges by 4.5 aswell!
3 x 4.5 = 13.5
So since it is 9:12 not 9:13.5 they are not in proportion