For infinitely many solutions, you must get each side of the equation to equal itself. So solve the first equation: 7 - 5 + 3x - 1
2 + 3x - 1
1 + 3x
Now make the blanks 3x and 1. For no solution, you can have anything other than x = an integer or x itself. If x = 2 + x, then it will have no solution. We have the solved equation: 1 + 3x. Fill in the blanks with 3x + any integer other than 1. For one solution, make it so x equals an integer. For example, you could fill in the blanks with 2x + 4, or anything other than 3x + 1 or 3x + any integer other than 1.