I have four pencils and Jack has seven pencils.
Jack gives me three of his pencils. How many pencils does Jack have left?
7-3 = 4 pencils
I have a whole pizza. I give half of my pizza to my sister. How much do I have left?
One half
I have 25 marbles. I loose 6 marbles but my brother gives me 10 of his marbles. How many marbles do I have now?
25 - 6 = 19 marbles
19 +10 = 29 marbles