The formula for amount of interest is the P*R*T. Because the principal is $650 dollars, and the rate is 4.5% for 1 year, the formula so far is 650*0.045*T. The interest is per annum or annual, so the time has to be in terms of years, which in this case is 1 year. This would give you 650*0.045. The answer for that is simply $29.25.
now we sub y + 16 in for d in the first equation y + d = 84 y + (y + 16) = 84 2y + 16 = 84 2y = 84 - 16 2y = 68 y = 68/2 y = 34 <=== yearbook club students
d = y + 16 d = 34 + 16 d = 50 <=== drama club students
