index.js

const employees = [
  {
    name: 'Renan',
    salary: 1000.00
  },
  {
    name: 'Vitor',
    salary: 980.50
  },
  {
    name: 'Marcos',
    salary: 2500.00
  }
]

const getSalaryDiff = (employeeA, employeeB) => employeeA.salary - employeeB.salary

const getSalarySortedEmployees = (employees) => {
  const salarySortedEmployees = [ ...employees ].sort(getSalaryDiff).reverse()
  return salarySortedEmployees
}

const getSalariesSum = (employees) => {
  const salariesSum = employees.reduce((sum, employee) => {
    return sum + employee.salary
  }, 0)
  return salariesSum
}

// ordeno e pego os 10 primeiros
const first = getSalarySortedEmployees(employees).splice(0, 10)

// somo os salários dos 10 primeiros
const sum = getSalariesSum(first)

console.log(sum)