The change for telephone calls, T,is partly constant and partly varies with the number n of unit of call.the bill for 420 unit of call is #806,while the bill for 200 unit is #410.find obtain the change per unit of call ,find a formular T

Answer 1

Show works

Answer 2

T = a+bn
a + 420b = 806
a + 200b = 410
subtract, and you get
220b = 396
b = 1.80
since that is the slope, it's also the unit rate per call.
now use that to find a, and then you have the formula for T

Answer 3

Not complete

Answer 4

Pls show workings