Addition and Subtraction: แบบฝึกหัด

What is the result of subtracting 8 from 20?

A baker has 42 cupcakes. He sells 18 cupcakes in the morning and 15 cupcakes in the afternoon. How many cupcakes does he have left at the end of the day?
\( 42 - 18 - 15 = ? \)

Sam has 64 marbles. He gives 28 marbles to Tom and then receives 15 marbles from Sarah. How many marbles does Sam have now?

Calculate the sum:
\(15 + 4 = ?\)

Mary had 50 stickers. She gave some to her brother and has 32 stickers left. How many stickers did she give away?

Calculate the sum of \( 14 \) and \( 23 \).

Find the difference between \( 58 \) and \( 16 \).

Tom has 12 red marbles and 15 blue marbles in a bag.
(a) How many marbles does he have in total?
(b) If he gives 7 marbles to his sister, how many marbles does he have left?