Answer:
day eight!!
Explanation:
Josh --> starts with $40, saving $10
Sal --> starts with $160, spending $5
day one: josh: $50, sal: $155
day two: josh: $60, sal: $150
day three: josh: $70, sal: $145
day four: josh: $80, sal: $140
day five: josh: $90, sal: $135
day six: josh: $100, sal: $130
day seven: josh: $110, sal: $125
day eight: josh: $120, sal: $120