Mathematical Equality

Mathematical Equality

Xavier is on a journey to find the hidden treasure.

Xavier comes across the treasure chest, but it is locked up. The math troll comes out and tells him he has to solve the problem in order to unlock the treasure.

"Balance the scale to unlock the chest. On one side we have a 7 pound rock and a 5 pound rock together. On the other side we have a 4 pound rock. How much should the other rock weigh?" asks the Troll.

Xavier sees the equal sign and assumes he needs to solve what is on the left of the equal sign, not realizing he needs to be balancing out the scale

"THAT IS INCORRECT" yells the Troll

"How is that wrong.. I know for a fact 7+5 is equal to 12.... wait, but the scale is still not balanced... Am I supposed to be balancing the scale???" - Xavier questions to himself

"Maybe I'm not reading the problem correctly. Maybe I am not solving an equation, but rather finding the balance between both sides... That means if 7+5=12, I must find what number plus 4 is also 12 to balance out both sides... I know that 12 minus 4 is 8, so the missing number MUST be 8!"

"I HAVE UNLOCKED THE TREASURE!... 7+5=8+4.. Today I learned about mathematical equalities. Both sides of the equal sign must balance out and represent the same quantity!"