The change c of a telephone company is partly constant and partly varies as the number of units of call u. The cost of 90units is 1120 and the cost of 120unit is1216.find a formula that connects c and u.find c when u is 150units

4 answers

c = ku + b
when u=90,c=120
1120 = 90k + b
when u=120, c=1216
1216 = 120k + b

subtract: 30k =96
k = 96/30= 16/5

go back into 1120 = 90k + b to find b

then form your equation,
so if u = 150 , c = .....
Solve the equation for me please in details please
Nonsense this is rubbish everyone don't do this nonsense the person is showing. ugh
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