Let's call the first number "x" and the second number "y".
From the problem, we know that:
- x = 15y + 10 (since "One number is 10 more than fifteen times another")
- x + y = 42 (since "Their sum is 42")
We can use substitution to solve for one of the variables. Substituting the first equation into the second equation, we get:
(15y + 10) + y = 42
Simplifying the left side, we get:
16y + 10 = 42
Subtracting 10 from both sides, we get:
16y = 32
Dividing both sides by 16, we get:
y = 2
Now that we know y, we can use the first equation to solve for x:
x = 15y + 10
x = 15(2) + 10
x = 40
Therefore, the two numbers are 2 and 40.