急問幾題數學題!!10~~

43.x/r(p-q)=pq find x
若你的式是
x/[r(p-q)]=pq
x = pqr(p-q)
若你的式是
x/r (p-q)=pq
x =pqr / (p-q)

44. x/p-q=x/r find x
x / p – x /r = q
x(1/p – 1/r) = q
x(r – p)/pr = q
x = pqr / (r – p)

46.Make b the subject of the formula k=4/ab-1/c
k=4/ab-1/c
k – 1/c = 4/ab
ab(k-1/c) = 4
b = 4 / [a(k-1/c)]
b = 4 / [a(kc-1)/c)]
b = 4c / [a(kc-1)]

47. Make m the subject of the formula PV=1/3Nmc2
PV=Nmc2/3
3PV = Nmc2
m = 3PV / (Nc2)

48a.Make r the subject of the formula p=a(1-r/100)
p=a(1-r/100)
100p=a(100 – r)
100p = 100a – ar
- ar = (100p – 100a)
r = (100a – 100p)/a

48b. find the value of r if p=180 a=200
r = (100a – 100p)/a
r = (100(200) – 100(180))/(200)
r = 10


49a.Make A the subject of the formula R=K(L/A)
AR = KL
A = KL/R

49b.find the value of A if R=100 K=60 L=20
A = KL/R
A = (60)(20)/(100)
A = 12

43.
x/r(p-q) = pq
x=rpq(p-q)

44.
x/p - q = x/r
x/p - x/r = q
x(1/p - 1/r) = q
x (r-p)/pr = q
x = prq/(r-p)

46.
k=4/ab-1/c
k - 1/c = 4/ab
ab(kc -1)/c = 4
b = 4c/a(kc-1)

47.
PV=1/3Nmc^2
3PV = Nmc^2
m = 3PV/Nc^2

48a.
p=a(1-r/100)
p/a = 1 - r/100
r/100 = 1 - p/a
r = 100(1 - p/a)

48b.
if p=180 A=200
r = 100 (1- 180/200)
r = 100 (20/200)
r = 10

49a&b.
Sorry ttah I cannot understand the question.