Mark counts six ducks in a pond and some ducks on the grass. there are ducks all l4. draw a picture to show the two groups of ducks

So 6 in pond
some on grass
# in pond+# in grass=14
6 in pond
subsitute 6 for pond
6+# in greass=14
subtract 6 from both sides
6-6+# in grass=14-6
0+# in grass=8
# in grass=8
there are 8 ducks in grass

so you would draw a circle for the pond and put 6 circles in there to represent the ducks, then , outside of that big circle, draw 8 circles to represent the 8 ducks on the grass (maybe label the big circle as pond and outside as grass)

50kg -  coffee A
100kg - coffee B

(coffee A)/ (coffee B) = 50kg/100kg = 1/2

1 + 2 = 3  Entire parts  
1/3 = coffee A
2/3 = coffee B

60kg * 2/3 = (120kg) : 3 = 40kg coffee B