To compare the size of two numbers a and B, sometimes we can solve it by the size of A-B and 0: if a = 5x + 2Y, B = 2x = 5Y, and X is less than y, try to compare the size of a and B

To compare the size of two numbers a and B, sometimes we can solve it by the size of A-B and 0: if a = 5x + 2Y, B = 2x = 5Y, and X is less than y, try to compare the size of a and B

a=5x+2y,b=2x-5y
a-b=3x-3y=3(x-y)