David had
16 as many marbles as Fabian. Fabian had twice as many marbles as Ben. If David had 84 marbles fewer than Ben,
- how many marbles did David have?
- how many marbles did they have altogether?
(a)
Number of marbles that David had = 1 u
Number of marbles that Fabian had = 6 u
Number of marbles that Ben had = 6 u ÷ 2 = 3 u
Number of marbles that David had fewer than Ben
= 3 u - 1 u
= 2 u
2 u = 84
1 u = 84 ÷ 2 = 42
Number of marbles that David had
= 1 u
= 42
(b)
Total number of marbles that they had
= 1 u + 6 u + 3 u
= 10 u
= 10 x 42
= 420
Answer(s): (a) 42; (b) 420
