Answer:
Explanation:
Let the tip be x.
You have to take 15% of 90 to get x.
The equation looks like
15/100 * 90 = x Multiply the numerator of the fraction by 90
1350/100 = x Divide by 100
x = 13.50
So the tip is 13.50
There are other ways you could do this problem, but I think this is the most easily understood.