Suppose a and b are integers. How many solutions are there to the equation ab = 2a + 5b?
Looks like four to me:
Wolfram gives the following numbers: https://www.wolframalpha.com/input/?i=+ab+%3D+2a+%2B+5b%2C+integer+solution
a = -5 and b = 1 a = 0 and b = 0 a = 3 and b = -3 a = 4 and b = -8 a = 6 and b = 12 a = 7 and b = 7 a = 10 and b = 4 a = 15 and b = 3
