The charge for telephone calls T,is partly constant and partly varies with the number n of units of call.The bill for 580 units of call is #900, while the bill for 310 units is #500.a.obtain the charge per unit of call.b find a formula for T.

Answer 1

You know that T = kn+b
So, you just have to solve for k and b in
580k + b = 900
310k + b = 500