This Year 4 maths worksheet looks quite straightforward, but many children will find it tricky.
Four numbers are shown as well as four addition and subtraction statements with missing numbers. Just put in the missing numbers from the four shown.
With the addition questions the best way to proceed is to look at the units digit of the answer to the number statement. Then look at the four numbers to see which two added together will match the units digit. Check that the answer is correct by adding in a different order or subtracting one number from the answer, to leave the other number.
For the subtraction statements again it is best to look at the units digit, but remembering that an adjustment from the tens might need to be made to reach the correct numbers.
This page can be found in the Year 4 resources, under Using and Applying Maths.