幫下我啦~~~~數學呀~~入黎啦...

let X = total amount of saving for 5%
Y = total amount of saving for 4%

as we know,
X+Y = 500 , X= 500-Y
X * 5% + Y * 4% = 22.2

=> (500-Y)*5% + Y*4% = 22.2
=> 25 - Y*5% + Y*4% = 22.2
=> 2.8 = Y *1%
=> Y = 280
X = 220

設X為年利率是5%的儲蓄，500-X 為年利率是4%的儲蓄
X x 5%+(500-X) x 4%=22.2
X 5/100+(500-X)4/100=22.2
5X/100+4(500-X)/100=22.2
5X/100+(2000-4X)/100=22.2
5X+2000-4X=22.2 x 100
X+2000=2220
X=2220-2000
X=220
年利率是5%的儲蓄=220
500-220=280
年利率是4%的儲蓄=280

形式A年利率=5%
形式B年利率=4%

設 $x 為在形式A的存款
和 $y 為在形式B的存款

x + y = 500__(1)
5%(x) + 4%(y) = 22.2
0.05x + 0.04y =22.2__(2)
(2) * 100, 5x + 4y = 2220__(3)
(1) * 4, 4x + 4y = 2000__(4)
(3) - (4), x = 220
代 x = 220 入 (1),
y = 280
∴x = 220, y = 280
∴兩種儲蓄各存了$220和$280