IF Joseph deposits $1,000 at year-end for the next 35 years, assuming he makes one yearly deposit of $1,000 at 5% compounded annually, how much interest would he earn?

amount = 1000(1.05^35 - 1)/.05

= 90320.31

without any interest he would have
35x1000 or 35000

so isn't the difference the interest he earns?