Answer:
Step-by-step explanation:
Given the first line has 10 marbles and each following line has one less, the general equation is the nth line will have 10-(n-1) marbles.
So the sixth line has 10-(6-1) = 5 marbles.
1st row: 10 marbles
each following row has one less
2nd row: 9
3rd row: 8
4th row: 7
5th row: 6
6th row: 5
so there are 5 marbles
