Answer:
he will pay 864 dollars in total
Explanation:
first we have to find 20% of 90 (i just rounded 89.99 to 90).
20% = 1/5, and 1/5 in decimal form is 0.20. (you can find the decimal value by multiplying the numerator and denominator by 10/10 and then simplifying it)
0.20 * 90 is 18, so we then add that to 90 making 108.
next, since Mark is buying 8 tickets, we multiply 108 by 8, giving us 864
therefore, 864 is our final answer