Answer: 3
Explanation: 5 times a number would be 5x, then increase that by 4 is 5x+4. The problem then says 5x + 4 ≥ 19. If we solve for x then we get x ≥ 3 so x has to be greater than or equal to 3, so the smallest number it could be is 3. You can even try any number smaller than 3 and see it doesn't work. even something like 2.9