Five times the sum of a number and 27 is greater than or equal to six times the sum of that number and 26. What is the solution set of this problem?
(-0, -21)
(-00,-21]
[-21, +00)
(21, +00)

let the number be x

5(x+27)>6(x+26)

5x+135>6x+156

5x-6x>135-156

-x>-21

×<21

(21,+00)

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.

a

b

d

step-by-step explanation: