Can anyone help me with this modular manipulation in system of equations? So i have to solve this system but i got stuck while computing and I need help.
m = 928377461;
x0 = 21380413;
x1 = 32564732;
x2 = 803330610;
a*x0+c === x1 mod m
a*x1+c === x2 mod m

I know the x's and m but I can't figure out reasonable equation to get a and c, because they have to be integers.
I considered:
a = ((x1 - (x1 * x1) - (x2 * x0)) / (x1 - x0)) mod m
c = (((x1 * x1) - (x2 * x0)) / (x1 - x0)) mod m

But they are not giving correct result (It's taken from linear congruential generator).
I would be really thankful if anyone could give me the correct formulas, cause i don't have a clue how am i supposed to solve it and everywhere i searched this part was described as a basic arithmetics, which seems to be too hard for me.

Ooookay...
$x_2 - x_1 \equiv ax_1 - ax_0 \equiv a(x_1-x_0)\pmod m$.
If $\gcd(x_1-x_0, m) =1$ then $x_1-x_0$ is invertible. So
$a \equiv (x_2 - x_1)(x_1-x_0)^{-1} \pmod m$
And the $c \equiv x_1-ax_0 \pmod m$.
So...
$x_1-x_0 = 11184319$ now use Euclid's Algorithm to find $\gcd(x_1-x_0, m)$ and solve $(x_1-x_0)^{-1}$.
$m = 928377461$
$928377461= 83*11184319 + 78984$
$11184319 = 141*78984+ 47575$ etc....
