Multi Op Amp Analysis
For op-amp problems, assuming negative feedback is present, the inverting and non-inverting inputs (ideally) have the same voltage.

Thus, for example, for the first op-amp, both inputs have a voltage of \$v_1\$.  So, how to proceed?

The correct node equation for node A is:

\$\dfrac{v_1 - V_{REF}}{R_2} + \dfrac{v_1 - v_x}{R_1} + \dfrac{v_1 - v_2}{R_F} = 0\$

Can you take it from here?