How can you recognize wheather a real world situation should be represented by an equation or an inequality Please answer ASAP

Adepartment store purchases screen-printed t-shirts at a cost of $5 per shirt. they mark up the price 150% (making the selling price 250% of the store's purchase price) and put them on the sales floor. every month that a t-shirt doesn't sell, the store reduces the selling price by 25%.

Write the equation in logarithmic form m^x=n

Given: circle o, cd is diameter, chord ab || cd. arc ab = 74°, find arc ca.