Variables (Integers)

Just as we can store a piece of text in a variable, we can also store numbers

age = 18
x = 1
print(age)
print(x)

With numbers we can perform operations

a = 2
b = 6
c = a + b
print(c)

c = a + b is very important to understand. If we have the = sign, what is on the right side is always executed first, then the result is stored in whatever is on the left side

x = 23 + 22

here 23 + 22 is done first. the result 45 is taken and stored in the variable x

Very often encountered in programming is incrementing by 1, meaning

n = 10
n = n + 1
print(n)

Why is 11 displayed? Or better said, why does the program run? Why doesn’t it crash? What do you mean n = n + 1? Mathematically this makes no sense Well, in programming, it does make sense. We already said that if we have an equals sign, Python first does what’s on the right, then stores the result in what’s on the left

n = n + 1

Here it looks to the right of the = sign and sees n + 1, meaning 10 + 1, which is 11, and it stores that in the variable n

By the way, 1, 2, 5, -1, -2019, 2025, 1235123, 0, all of these are integers There are also floating-point numbers, meaning with decimals, such as 3.14 or -15.6

pi = 3.14159
k = 33

print(pi + k)

this displays text 36.159

Mission: Oxygen Count

The station has three oxygen tanks, with their amounts (in liters) stored in tank_a, tank_b, and tank_c.

Add the three tanks together into a total and print it. Then a leak drains 50 liters, so subtract 50 from the total and print the new value.

Input (already set at the top of your code, change the values to test):

• tank_a, tank_b, tank_c: liters of oxygen in each tank

Example

With the starter values, your program should print

400
350