Given that La + 1 and lb-2l are opposite to each other, we can find the value of a-b OK, more

Given that La + 1 and lb-2l are opposite to each other, we can find the value of a-b OK, more

La + 1 and lb-2l are opposite numbers
Then a + 1 = 0, B-2 = 0
a= -1 b=2
a-b= -1-(-2)=1