At what week will Mary and Emily have the same amount of money?

Question

Mary has $75 and earns $20 per week. Emily has $100 and earns $10 per week. At what week will Mary and Emily have the same amount of money?

Answer 1

75+20W = 100+10W

20W-10W = 100-75

10W = 25

W = 25/10 = 2 1/2 weeks they'll have the same amount of money (if they don't spend any, which is unlikely)

In 2 weeks Mary will have 115, Emily will have 120

in 3 weeks Mary will have 135, Emily will have 130

in 2 1/2 weeks Mary will have 125, same as Emily (assuming they get paid in half a week)