How to change -10;10V sine wave to 0;3.3V dor ADC
simulate this circuit &ndash; Schematic created using CircuitLab

From the Kirchhoff's Voltage Law:

$$
V_o = \dfrac{\dfrac{V_i}{R_i} + \dfrac{V_1}{R_1} + \dfrac{V_2}{R_2}}{\dfrac{1}{R_i} + \dfrac{1}{R_1} + \dfrac{1}{R_2}}
$$

In your case, we have three known input-output relationship:

$$
V_i = +10V \implies V_o = +3.3V \\
V_i = 0V \implies V_o = +1.65V \\
V_i = -10V \implies V_o = 0V
$$

This gives you three equations with five unknowns. If you fix some variables to reasonable values, for example \$V_1=10V\$, \$V_2=-5V\$, \$R_i=10k\Omega\$, you can easily calculate the remaining variables (i.e.; \$R_1\$ and \$R_2\$).