What should you do if in the review phase of problem solving you find the answer doesn't make sense?

How long must $542 be invested at a rate of 7% to earn $303.52 in interest? in a easier way

Which shows a reasonable estimation for 124% of 42 using the distributive property?

Apassenger train and a freight train leave san jose at 3pm, traveling in the same direction. the passenger train is going three times as fast as the freight train. at 6pm they are 240 miles apart. how fast is each travelling? explain your answer and show your