(a) Barbara wants to accumulate $10000 by the end of 10 years. She starts making quarterly deposits in her investment account, which pays J4 - 8%. Determine the size of these deposits. (b) After 4...

(a) Barbara wants to accumulate $10000 by the end of 10 years. She starts making quarterly deposits in her investment account, which pays J4 - 8%. Determine the size of these deposits.
(b) After 4 years, the rate of return changes to j4 = 6%. Determine the size of the quarterly deposits now required if the $10000 goal is to be met.

Please don't use excel and tell me everything with using formula because ı can't understand without formula