1.7 3 test cst expressions equations and inequalities

Brent works part-time at a clothing store. he earns an hourly wage of $15. if he needs to earn more than $45 in a day and works for x hours a day, which inequality represents this situation? a. 15x > 45 b. 15x < 60 c. x > 60 d. 15x < 45 e. x < 60

I'm confused on this could anyone me and show me what i need to do to solve it.

3x + 4y = 5 x- 3y = -7 solve by substitution