The expression of the total cost can be divided in 2 parts, the one that represents the amount she has to pay per hour of reparation and the one that represents the taxes she has to pay over that amount.
The first part is 70h, and it represents the amount she pays when it takes h hours to repair her computer.
The second part is 0.08(70h) that represents the taxes, that are 8% of the cost of reparation. It means that the answer is 0.08(70h).