Question

the monthly charge C of an electricity company is made up of follows:A constant charge a and A charge which varies directly as N the number of units used . when N=80 C =820 naira . When N =124 , C =1040 naira find the relationship between C and N ,find C when N = 180

Answer 1

c = a + n k

820 = a + 80 k
1040 = a + 124 k
-----------------subtract
-220 = -44 k

so k = 5
820 = a + 80*5 = a + 400
a = 420
so
c = 420 + 5 n

if n = 180
then
c = 420 + 80(180)
c = 420 + 14,400
c = 14,820

Answer 2

N♾C
N=KC
80=K(820)
K=80/820
K=4/41
The relationship (N=4/41C)