So we already have 30 dollars saved from our job, so that means if we worked no more hours, we'd still have that 30 dollars saved from work. But in our case, we still need to work so we can purchase the calculator. So we earn $7.50 per hour, and then we already have the $30 saved from work, which is going to go toward the calculator, which will cost at most $115.

So our equation is:

7.50x+30 <= 115, since we want to put money toward the calculator. So that is the equation you will want to solve so you can buy that calculator. Hope this helped you!