Question

PLEASE DO NOT OMIT STEPS, EXPLAIN IT DETAILED MIND PLEASE, ALSO WRITE BIG SO THAT I CAN LOOK AT IT AS I CAN CONFUSE THANK YOU VERY MUCH!

THIS PROBLEM ALMOST ALWAYS RESOLVED ONLY THAT I HAVE PROBLEMS WITH THE UNITS AT THE END BECAUSE I WAS SEEING THE SOLUTION AND I SEE THAT TWO LAST CONVERSIONS DO NOT APPEAR TO ME TO BE INECESSARY. CAN YOU EXPLAIN ME WHY THAT IS DONE?
IN THE IMAGE OF THE PROBLEM THAT IS IN THE SOLUTION, I MADE MY OPERATION FOR YOU TO LOOK BECAUSE I TOLD YOU THAT FOR ME IS INCESARIO, I ONLY MAKE A CONVERSION AT THE END

my answer is 7.335 psi but the one in the book is 0.227 psi

a tube in a u has its branches open to the atmosphere. Then, equal volumes of water and light oil (P = 49.3 lbm / ft ^ (3)) are poured into the branches. A person blows on the oil side of the U-tube, until the contact surface between the two liquids moves to the bottom of the U-tube, so that the liquid levels in the two branches are equal. If the height of the liquid in each branch is 30 inches, calculate the manometric pressure exerted by the person when blowing.

IMAGE THE PROCEDURE OF THE SOLUTION WITH IMAGE OF THE PROBLEM https://plus.google.com/photos/photo/115413650822843498915/6534846094405577378?authkey=CIKa-_-Ar9rTCQ&hl=es

Answer 1