Answer:
6m 48cm
Explanation:
First we can convert the length of Mac's bedroom to centimeters:
As<em> 1 m is equal to 100 cm</em>,
- 3m 59cm is equal to 300 cm + 59 cm = 359 cm.
As for Dennis' bedroom's information:
Now we can calculate the length of Dennis' bedroom:
Rewriting the answer leaves us with 6m 48cm.

that is the answer, but what is the y value?
Answer:

Explanation:
The second line in the Pfund series corresponds to a transition from n = 7 to n = 5.
To calculate the wavelength of the transition, we can use the Rydberg equation:

where

If n₁ = 5 and n₂ = 7


Au :)
Pb + Cu(2+)---> Pb(2+) + Cu
Mg + Cu(2+)---> Mg(2+) + Cu
2Na + Cu(2+) ---> 2Na(+) + Cu
Au + Cu(2+) ---> (this reaction is not possible)