Final answer:
The question pertains to the addition and subtraction of 2-digit numbers in mathematics, particularly focusing on the proper alignment of numbers, carrying and borrowing, the commutative property for addition, converting between different units for compound problems, and dealing with significant figures.
Step-by-step explanation:
Understanding Addition and Subtraction of 2-Digit Numbers
The student's question deals with the addition and subtraction of 2-digit numbers, two fundamental operations in mathematics. When working with these operations, the basic principle to keep in mind is the proper alignment of numbers according to place value. For addition, one important concept is the commutative property, which is illustrated by the equation A+B=B+A, showing that the order in which numbers are added does not affect the sum. The same principle does not apply to subtraction. When dealing with subtraction, it's important to pay attention to which number is the subtrahend (the number being subtracted) and which is the minuend (the number from which another number is subtracted).
In addition, when performing addition and subtraction with whole numbers, attention must be paid to carrying over in addition (or 'carrying') and borrowing in subtraction. For exercises involving compound unit problems and metric units, understanding how to convert between different units is also important. Finally, when considering significant figures in addition and subtraction, it's essential to align decimal points and round off the result accordingly.