# Mathematics

The cost of a car service is partly constant and partly varies with the time it takes to do the work .if cost 3500 naria for a 5 1/2 hour service and 2900 naira for a 4 hour service. Find the formula connecting cost , naira C with time ,T hours, hence find the cost of a 7 1/2 hour service.

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1. cost = mt + c, where t is the number of hours and c is your constant
given: whn t = 5.5, cost = 3500
3500 = 5.5m + c
given: when t = 4, cost = 2900
2900 = 4m + c
subtract those two equations,
600 = 1.5m
m = 400
sub back into 2900 = 4m + c
2900 = 1600 + c
c = 1300

now you have the complete cost equation
cost = 400t + 1300

sub in your other time and proceed

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Reiny
2. good
what abt the formula

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4. What of the second solution

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