Can you move the upper jaw?

Why cannot we move upper jaw ?

When you added a positive integer, in which direction did you move on the number line?

When you subtract a negative integer, in which direction do you move on the number line?

When you added a negative integer, in which direction did you move on the number line?

When you subtract a positive integer in which direction do you move on the number line?

Can you name the test shown in the figure ?

Guess who I am I am a joint between upper jaw and skull.

A double decker minibus has 8 seats in the lower deck and 10 seats in the upper deck. Find the number of ways of arranging 18 persons in the bus if 3 children want to go to the upper deck and 4 old people can not go to the upper deck.