小学题用两种方法计算15-3？

Question

小学题用两种方法计算15-3？

Answer 1

(1)
15-3
=(12+3)-3
=12+3-3
=12+(3-3)
=12+0
=12
(2)
15-3
=15-(5-2)
=15-5+2
=(15-5)+2
=10+2
=12