Plz answer this mathematics question with complete calculating steps plz.thx?

(a)When Charles's first child, John is born, Charles invested RM300 for him at 8% compound interest per annum. He continues to invest RM300 on each of John's birthday, up to and including his 18th birthday.What will be the total values of the investment on John's 18th birthday?(b)If Charles starts his investment with RM500 instead of RM300 at the same interest rate, calculate on which birthday will the total investment be more than RM25000 for the first time.RM can be said as $the answer for the question (a) is RM1198.79 an d the answer for (b) is RM25171.42.i juz need the steps of calculations now.

P = C (1 + r) twhere P = future value C = initial deposit r = interest rate (expressed as a fraction: eg. 0.06) n = # of times per year interest in compounded t = number of years invested(a) P = C (1 + r) tP = 300(1 + .08)18P = 300(1.08)18P = $5832(b) 25000 = 500(1 + .08)t25000 = 500(1.08)t25000 = 540t25000/540 = (540/540)t46.30 = t --> on his 47th birthday the total investment will be more than $25000 for the first time