Putting variables together

Question

I have two equations with multiple variables and I wonder if I can use them in a way that I have less variables in the end.

$A_t = 2a +2b+4h+bh_r+2ac$

and

$h+h_r=h_t$

Thanks in advance.

Answer 1

Note that $h_t$ doesn't show in the equation $A_t = 2a +2b+4h+bh_r+2ac$, so when you substitute $h$ or $h_r$ you introduce another variable $h_t$. The only you can do is so: $$A_t = 2a +2b+4(h_t-h_r)+bh_r+2ac=2a +2b+4h_t+(b-4)h_r+2ac$$