Since both numbers are in the ones place, you can add them together directly. That gives you

You can think like this:

• The number $12$ has $1$ in the tens place and $2$ in the ones place.

• The number $25$ has $2$ in the tens place and $5$ in the ones place.

• First, you add the numbers in the ones place together. That gives you

  $$2+5=7$$

• Then you can add the numbers in the tens place together. That gives you

  $$1+2=3$$

• You have $3$ in the tens place and $7$ in the ones place. That makes the answer $37$, which means that

  $$12+25=37$$

Since both numbers are in the ones place, you can subtract directly. That gives you

In this case you can think like this:

• The number $48$ has $4$ in the tens place and $8$ in the ones place.

• The number $25$ has $2$ in the tens place and $5$ in the ones place.

• First, you need to subtract the numbers in the ones place from each other. That gives you

  $$8-5=3$$

• Then you can subtract the numbers in the tens place from each other, which gives you

  $$4-2=2$$

• You now have $2$ in the tens place and $3$ in the ones place. That means the answer is

  $$48-25=23$$