Leo invested a certain amount of money for one year. He invested $1,00

I think
"If the amount that Leo invested at c percent annual interest and the amount that he invested at d percent annual interest earned $30 in interest for that year" means each of the amounts are getting an interest of $30.

If yes, then We can simply use each of the statements alone to find the total amount.

We know 1000*c*1/100 = 30, we can find out c=3.

Also, let total amount is X.

We can say (X-1000) * d*1/100 = 30.

Now, as per statement 1, we know c-d=1. We have the value of c, this would give us teh value of D and which in turn when substituted to equation above will give X.

Same goes for statement 2.

Hence, D

Please correct me if I am missing anything.