Let the number of History books be x. Then:-
x + x - 59 = 343
2x = 402
x = 201
So there are 201 History books and (201 - 59) = 142 Chemistry books.
Well the answer would be 12.5. I hoped that this helped. :)
67.3 repeating. You multiply 68 times 50, subtract 82 and 86, them divide by 48. If that doesn't work, try dividing by 50. That should work.
Answer:
The surface area is 125.66 
Hope this helps!