@rlopez 

i think it makes more sense to say that i need to run maybe 500 calculations with a T = from 1 to 500, starting from 1 going towards 500.

where the loop should stop running when my result T_new is the same as T.

T=1..500:

calc bla bla bla  

when, T_new= T, loop stop 

in my calculations, when i run it manuelly, the T_new will decrese as the T increses until they are the same and i then know my T when T = T_new

hope i makes sense (: thanks 

@vv 

Thanks so much!! 

worked like a charm.

i tried to solve it like this:

l1:=21000 = ((10/1000)/60)*4181*983*(x-y)

l2:=H = -((10/1000)/60)*4181*ln(1-((x-y)/(x-40)))

l3:=H = 124+102*ln(x-40)+(7+2*ln(x-40))

solve([L1,L2,L3],[x,y,H])

and i got the message:

Warning, solutions may have been lost
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