Answer:
To find the greatest possible value of x + y, we need to maximize the values of x and y such that they are still positive integers and satisfy the given equation 18x + 11y = 2020.
We can start by rearranging the equation to solve for y:
11y = 2020 - 18x
y = (2020 - 18x)/11
For y to be a positive integer, 2020 - 18x must be divisible by 11. We can test values of x starting from x = 1 and increasing by 1 until we find the largest possible value of x that satisfies this condition.
When x = 1, 2020 - 18x = 2002, which is divisible by 11. This gives us a value of y = 182/11, which is not a positive integer.
When x = 2, 2020 - 18x = 1984, which is divisible by 11. This gives us a value of y = 180/11, which is not a positive integer.
When x = 3, 2020 - 18x = 1966, which is divisible by 11. This gives us a value of y = 178/11, which is not a positive integer.
When x = 4, 2020 - 18x = 1948, which is divisible by 11. This gives us a value of y = 176/11, which is not a positive integer.
When x = 5, 2020 - 18x = 1930, which is divisible by 11. This gives us a value of y = 174/11, which is not a positive integer.
When x = 6, 2020 - 18x = 1912, which is divisible by 11. This gives us a value of y = 172/11, which is not a positive integer.
When x = 7, 2020 - 18x = 1894, which is divisible by 11. This gives us a value of y = 170/11, which is not a positive integer.
When x = 8, 2020 - 18x = 1876, which is divisible by 11. This gives us a value of y = 168/11, which is not a positive integer.
When x = 9, 2020 - 18x = 1858, which is divisible by 11. This gives us a value of y = 166/11, which is not a positive integer.
When x = 10, 2020 - 18x = 1840, which is divisible by 11. This gives us a value of y = 164/11, which is not a positive integer.
When x = 11, 2020 - 18x = 1822, which is divisible by 11. This gives us a value of y = 162/11, which is not a positive integer.
When x = 12, 2020 - 18x = 1804, which is divisible by 11. This gives us a value of y = 160/11, which is not a positive integer.
When x = 13, 2020 - 18x = 1786, which is divisible by 11. This gives us a value of y = 158/11, which is not a positive integer.
When x = 14, 2020 - 18x = 1768, which is divisible by 11. This gives us a value of y = 156/11, which is not a positive integer.
When x = 15, 2020 - 18x = 1750, which is divisible by 11. This gives us a value of y = 154/11, which is not a positive integer.
When x = 16, 2020 - 18x = 1732, which is divisible by 11. This gives us a value of y = 152/11, which is not a positive integer.
When x = 17, 2020 - 18x = 1714, which is divisible by 11. This gives us a value of y = 150/11, which is not a positive integer.
When x = 18, 2020 - 18x = 1696, which is divisible by 11. This gives us a value of y = 148/11, which is not a positive integer.
When x = 19, 2020 - 18x = 1678, which is divisible by 11. This gives us a value of y = 146/11, which is not a positive integer.
When x = 20, 2020 - 18x = 1660, which is divisible by 11. This gives us a value of y = 144