Suppose the two Numbers are X and Y.
X + Y = 58
Suppose X is the larger number
X = 3Y - 10 According to the text
Plug X into the first equation to get 3Y + Y = 58 so Y = 14.5
Since Y = 14.5, plug this in the first equation and get Y = 43.5
Ans: 14.5 and 43.5
Hope this helps :)