You answer is In 18 weeks he'll have the $400 for the new phone.
I know this because she needs 400 but already has 130 so (400-130=270)
This means that Ruby is missing 270 to get to the 400 that he needs for the phone.He gets $15 per week so now that's (270/15=18).Which means that in 18 weeks Ruby will complete to full $400 that he needs for a new phone.
