exam Maths Puzzle Numerical Ability

How would you solve this. I got 0 & -1 but they dont plug in the solution right.
5x^2-5x=0

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exam Other Question

This is asking to find the distance between (6,0)and (-7,0)

I am getting stuck on the first step, how do bracket (0,0)?
please help i know how to do linear combination, but i cannot get the right answer for this problem:
2x+y+52=2y+50
2x+y+52=x-3y+131

I need help finding x and y.

Thank you!