Hello, i cant seem to wrap my head around this question

You want to invest 100 dollars every two weeks at 7 percent compounded monthly for the next 40 years. how much money will you have at the end of 40 years?

its driving me to

i would like to see a formula for this that does not involve calculating interst on each instance of 100 dollars for a massive chain equation. you can use 200 invested monthly to make it easier since you only earn interest monthly anyways but man i cant think