F.3 Maths Questions 40pts!

1. 題目唔寫，我直接約
[(2^n)(2^4) - 3(2^n)(2^3)] / (2^n)(2^2)
= [16(2^n) - 24(2^n)] / 4(2^n)
= -8(2^n) / 4(2^n)
= -2

2. 題目唔寫，我直接約
[(x+ xr/100) - x] / x = 0.25
xr/100 * 1/x = 0.25
r/100 = 0.25
r = 25

As follows:


圖片參考：http://i.imagehost.org/0693/ScreenHunter_01_Dec_29_18_51.gif