Question

millie has a box of 1 hundred cubes. she also has a bag of 70 cubes. How many trains of 10 cubes can she make?

Answer 1

17 trains
is the right answer just count by tens until you get to 170 

Answer 2

Millie has box which contains 100 cubes 
She has a bag which contain 70 cubes
so total cubes she has is 170 cubes

If she is making a train of 10 cubes so,
170 / 10 ( because one train has 10 cubes)
= 17 trains out of 170 cubes.

Ans = 17 trains
:) hope I helped you