Well you basically use rise/run so basically you choose two points on the line and you count how many squares it goes up until its on the same line as the other point and then you count how many squares to the side to get to the other point so rise/run ill explain it a lil better
We need to find the base x in the following equation:

First, lets convert 365 from base 7 to base 10. This is given by

where the upperindex denotes the position of eah number. This gives

that is, 365 based 7 is equal to 194 bases 10.
Now, lets do the same for 43 based x. Lets convert 43 based x to base 10:

where again, the superindex 0 and 1 denote the position 0 and 1 in the number 43. This gives

Now, we have all number in base 10. Then, our first equation can be written in base 10 as

For simplicity, we can omit the 10 and get

so, we can solve this equation for x. By combining similar terms. we have

and by moving 197 to the right hand side, we obtain

Finally, we get

Therefore, the solution is x=5
Steps to solve:
5x² = 15x
~Subtract 15x to both sides
5x² - 15x = 15x - 15x
~Simplify
5x² - 15x = 0
~Factor left side
5x(x - 3) = 0
~Factors equal 0
5x = 0 and x - 3 = 0
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~Simplify 5x = 0
5x/5 = 0/5
x = 0
~Simplify x - 3 = 0
x - 3 + 3 = 0 + 3
x = 3
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Thus, the correct answer is 0, 3.
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Best of Luck!