It would not be fair to tell you!

Basically, it's algebra.

You can use x and y or a and b.

Here's a clue "There are 2 things you do not know"

the amount that 5% interest is earned from and the amount 8% interest is earned from.

What do we know?

They generate $100 interest, which means the sum of the 2 interests is $100.

Also we know that the 2 amounts themselves sum to $1400.

To find 2 values you need 2 clues.

Are you familiar with solving simultaneous equations,

like 2x+5y =7 and 3x-y =4 ??

This is the same.

So what is x+y ?

Also what is x(5/100) + y(8/100) ?

Try to figure that out