Last year, Amy had $20000 to invest. She invested some of it in an account that paid 8% simple interest per year, and she invested the rest in an account that paid 9% simple interest per year. After one year, she received a total of $1690 in interest. How much did she invest in each account?

Amount invested at 8% rate of interest = $11000

Amount invested at 9% rate of interest = $9000

Step-by-step explanation:

Let Amy invested amount in a account with 8% simple interest = $a

Then the interest gained after one year =

                                                                  =

                                                                  = 0.08a

Remaining amount for the investment = $(20000 - a)

Interest earned after one year with rate of interest 9%

=

= $(1800 - 0.09a)

Total interest earned after 1 year = $1690

0.08a + (1800 - 0.09a) = 1690

1800 - 0.01a = 1690

0.01a = 110

a = $11000

Amount invested at 8% rate of interest = $11000

Amount invested at 9% rate of interest = $(20000 - 11000) = $9000

if you are saying purchasing 3 social media ads and one newspaper ad counts as one purchase then there are:

6 purchases

if you are asking how many of each then:

18 social media ads

6 newspaper ads