For the first equation, to get an equation that only has 1 solution your two missing numbers could be 3x and 6. This is because when you solve it, you get 7x + 2 = 3x + 6
- 3x
4x + 2 = 6
- 2
4x = 4
x = 1
For the second equation, your two numbers could be 7x and 4, because it means that x has to be different as 7 multiplied by one number and added to 2 cannot equal 7 multiplied by the same number but added to 4.
I hope this helps!