Calculate the formula according to the meaning of the question:
Learn dance+calligraphy-both.
= 120+ 100- 10
=220- 10
=2 10
So a * * * has 2 10 people.
Arithmetic operation of addition and subtraction:
Integer addition and subtraction, the same digits are aligned, starting with single digits, and when the addition reaches ten digits, the higher digits will be entered; If the subtraction is not enough, subtract 1 from the high position. When this number is added to 10, it will decrease.
A number minus the difference between two numbers is equal to this number minus the minuend in the difference, and then the subtraction. For example:100-(32-15) =100-32+15 = 68+15 = 83. If you subtract a number from the sum of several numbers, you can choose any addend to subtract this number and add it to the rest of the addends.