Company A : 15h + 20
Company B : 5h + 40
when would company B be cheaper....
15h + 20 > 5h + 40 ...put the less then sign towards Company B, then solve
15h - 5h > 40 - 20
10h > 20
h > 20/10
h > 2
Company B would be cheaper when the hours (h) are greater then 2