Solving story problems

I am learning to solve addition and subtraction at level 3  

1.  Maraea is saving to buy a cat.  In 3 weeks she has saved $9, $56 and $72.

Show how to work out how much she has saved altogether

70+50=120

9+6+2=17

120+17=137                    

2.  Tom saves his money each month to buy a dog.  In 4 months he has saved $36, $78, $203, and $123.  Show how to work out how much he has saved altogether.

200+100=300

300+70=370

370+30=400

400+20=420

420+10=430

430+10=440 -> Answer: 440

3.   Te Ao is saving to buy a horse.  So far she has saved $17, $160, $72, and $148.  Show how to work out how much she has saved altogether.

100+100=200

200+80=280

280+70=350

350+40=390

390+8=398

398+2=400

400+7=407

407+60=467   -> Answer: 467

4.  Petelo has $ 147 as a present.  He spent $78 at the shop.  How much has he got left?

100-70=30

30-8=22

22+40=62

62+7=69 -> Answer: 69