i need step by step explanation for this!

Answer:
61
Step-by-step explanation:
Therefore, the number is 61
Let's check:
The sum of the two digits is 13, and we got that, so we are correct. The number is 61.
Answer:
49
Step-by-step explanation:
let unit digit=x
ten's digit=y
then x+y=13
x=13-y
also x=2y+1
13-y=2y+1
13-1=2y+y
3y=12
y=12/3=4
x=13-4=9
so number =10×4+9=49