If anyone has the time and is willing to program a brute-force search for the following 6 equations, with the noted constraints, I will give them a cookie or something. I know nothing of programming, or I would do it myself.
Constraint 1: all variables are non-negative integers (0, 1, 2, ...)
Constraint 2: all variables have a minimum of 0 and a maximum of 20.
Constraint 3: L is not 0.
Equations:
4 = (A(BC+D(1+ROUNDDOWN(L/3)))+E)/((F(G(H+I)+J)+(1+ROUNDDOWN(L/3))x(7+ROUNDDOWN(L/3)))-(4+ROUNDDOWN(L/3)))
4 = (A(BC+D(1+ROUNDDOWN(L/3)))+E)/((F(G(H+I)+J)+(1+ROUNDDOWN(L/3))x(4+ROUNDDOWN(L/3)))-(7+ROUNDDOWN(L/3)))
4 = (A(BC+D(4+ROUNDDOWN(L/3)))+E)/((F(G(H+I)+J)+(1+ROUNDDOWN(L/3))x(7+ROUNDDOWN(L/3)))-(1+ROUNDDOWN(L/3)))
4 = (A(BC+D(4+ROUNDDOWN(L/3)))+E)/((F(G(H+I)+J)+(1+ROUNDDOWN(L/3))x(1+ROUNDDOWN(L/3)))-(7+ROUNDDOWN(L/3)))
4 = (A(BC+D(7+ROUNDDOWN(L/3)))+E)/((F(G(H+I)+J)+(1+ROUNDDOWN(L/3))x(4+ROUNDDOWN(L/3)))-(1+ROUNDDOWN(L/3)))
4 = (A(BC+D(7+ROUNDDOWN(L/3)))+E)/((F(G(H+I)+J)+(1+ROUNDDOWN(L/3))x(1+ROUNDDOWN(L/3)))-(4+ROUNDDOWN(L/3)))
I'm looking for all valid solutions. There are 120(21^10) configurations, which are just a few too many for me to try myself...