Last year, Amy had $30,000 to invest. She invested some of it in an account that paid 9% simple interest per year, and she invested the rest in an account that paid 5% simple interest per year. After one year, she received a total of $1780 in interest. How much did she invest in each account?

Okay so n is going to represent our first number. since the second number of five times greater than n, the second number will be represented as 5n. for us to figure out the two  numbers we need to have  the value of n first. this is going to be done by adding the two numbers together, n and 5n. it can be simplified as 6n, which the problem states is equal to 72. divide 72 by 6n and you can solve for n.  n+5n=726n=72n=(72/6)n=12  now that we know the value of n, we have to multiply 5 times 12 which equals 60. so our two numbers/integers are 12 and 60