The answer is 52
x - the number of students in a bus
4 + 9x = 472
9x = 472 - 4
9x = 468
x = 468 / 9
x = 52
Using the combination formula, it is found that she can select the shirts in 775,200 ways.
The order in which the shirt are chosen is not important, hence, the <em>combination formula</em> is used to solve this question.
Combination formula:
is the number of different combinations of x objects from a set of n elements, given by:
In this problem:
- 3 shirts from a set of 17.
- Then, 3 shirts from a set of 20.
- They are independent, hence, to find the total, we multiply both combinations.

She can select the shirts in 775,200 ways.
To learn more about the combination formula, you can check brainly.com/question/25821700

<h3>Further explanation</h3>
We will calculate the unit conversion factor used to convert its engine displacement from cubic-centimeters to cubic-inches.
The relationships between inch and cm are as follows:

Inches and cm represent units of length.
Made into fractions, 1 inch as the denominator and 2.54 cm as the numerator.

As a unit conversion factor of volume, the numerator and the denominator in cubic.


Thus, we get the unit conversion factor

Let's use this unit conversion factor to calculate its engine displacement in new units.

Note for cm³ units that have been crossed out.
The conversion result is 
<h3>Learn more</h3>
- Convert cubic-kilometers to cubic-meters brainly.com/question/1446243
- How to write in scientific notation brainly.com/question/7263463
- Calculating mass based on density and volume brainly.com/question/4053884
Keywords: the motorcycle engine, Kawasaki Ninja 1000, 1043 cubic-centimeters (cm³), to calculate, its engine displacement, in cubic-inches (in³), what unit conversion factor
The answer to this is 7.5.