Answer:
93% probability of a student taking a calculus class or a statistics class
Step-by-step explanation:
We solve this problem building the Venn's diagram of these probabilities.
I am going to say that:
A is the probability that a student takes a calculus class.
B is the probability that a student takes a statistics class.
We have that:

In which a is the probability that a student takes calculus but not statistics and
is the probability that a student takes both these classes.
By the same logic, we have that:

The probability of taking a calculus class and a statistics class is 0.07
This means that 
The probability of taking a statistics class is 0.90
This means that
. So



The probability of a student taking a calculus class is 0.10
This means that 



What is the probability of a student taking a calculus class or a statistics class

93% probability of a student taking a calculus class or a statistics class
What are you supposed to solve???
If you start on page 20 and end on Page 50, you will have read 31 pages. I just counted from 20 to 50, including the number 20 in it.
OR: You already know there are 50-20=30 pages. But that's without counting the 20 in it. So when you add the extra 20: 30 + 1 = 31
Translated version:
Если вы начнете со страницы 20 и закончите со страницы 50, вы прочтете 31 страницу. Я только что насчитал от 20 до 50, включая число 20 в нем.
ИЛИ: Вы уже знаете, что 50-20 = 30 страниц. Но это без учета 20 в нем. Поэтому, когда вы добавляете дополнительные 20: 30 + 1 = 31
Я использовал Google Translate, поэтому результаты могут быть неточными.
The answer to the question is X=1/3
No she will not have enough money