We know there is a total of 100 cups of tea sold and that there are two types of teas involved.
x = tea 1
y = tea 2
We can set up two equations and use substitution to solve:
x + y = 100 cups of tea sold total
One of the teas sold 5 times as much as the other. Let's believe that this was tea 1:
x = 5y (5 times as much means multiplication, and 'other' means y)
If x = 5y, then this must be true for the first equation. So we'll test this by plugging it in:
5y + y = 100
6y = 100
y = about 16.67
Now we can use this number to solve for x in the original equation:
x + 16.67 = 100
x = 83.33