Consider the equation 4+2 (5x-8) = ax+b for what values of a and b would the equation have infinitely many solutions

Remove the brackets on the left.

4 + 10x - 16 = ax + b

10x - 12 = ax + b

If a = 10 and b = - 12 then x can be anything and equality would be true.

So for example let x = 400

10*400 - 12 = 10*400 - 12

4000 - 12 = 4000 - 12

3988 = 3988

You could put in any number you wanted to for x and the results would be equality but meaningless.