Hello, dianna,

let C be the costs for/of the service

let t be the hours you are online

Then the costs can be calculated by:

States online: C = 2.95 + 0.3*t

Big Neat online: C = 4.95 + 0.1*t

Now plug in t = 51 and you'll get:

SO: C(51) = $18.25

BN: C(51) = $10.05

By the way: At t = 10 h both providers want $5.95

EB