A company pays project contractors a rate of a dollars for the…

A company pays project contractors a rate of a dollars for the first hour and b dollars for each additional hour after the first, where a > b. In a given month, a contractor worked on two different projects that lasted 4 and 6 hours, respectively. The company has the option to pay for each project individually or for all the projects at the end of the month. Which arrangement would be cheaper for the company and how much would the company save?

This problem repeats another one in the library (at most with different numbers), so it's left out of browsing.

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #9281