If $28+20=48$28+20=48, what is the answer to $28+18$28+18?

If $43+20=63$43+20=63, what is the answer to $43+22$43+22?

If $90-26=64$90−26=64, what is the answer to $91-26$91−26?

If $80-23=57$80−23=57, what is the answer to $78-23$78−23?

Use simple additive strategies with whole numbers and fractions

Generalise that whole numbers can be partitioned in many ways