Find the part that is not shown
A missing-number equation hides one part of a complete arithmetic fact. Use the operation, the known number and the result to identify the hidden value.
For □ + 5 = 12, find the addend that joins 5 to make 12. For 15 − □ = 9, keep the ordered subtraction fact in view and find the missing subtrahend.
Count from 5 up to 12 to find 7 for the first blank. In the second equation, 15 must lose 6 to leave 9. The unknown is an addend in one task and the amount taken away in the other, so choose the matching practice before starting.