### Two questions about parameters in solutions

In the Sage documentation, this example is given:

```
sols = solve([x+y == 3, 2*x+2*y == 6],x,y); sols
```

of a solution which includes an extra parameter:

```
[[x=?r1+3,y=r1]]
```

- If I run this comand again, the solution is given with r2, then again with r3 etc. Is it possible to "reset" the parameter number?
How does one substitute a particular value for this parameter? I can do it by iterating through the list and using rhs():

```
[i.rhs().subs(r1=1/2) for i in sols]
```

or by setting solution_dict=True and fiddling another way:

```
[sols[i].subs(r1=1/2) for i in [x,y]]
```

Neither of these seem particularly elegant - is there a more "natural" way?