12. Alex, Ben and David went for a run but none of them completed the run.
Ben ran 5 times as far as Alex before he stopped.
David stopped 1 km before the finishing line and he ran 3 km less than twice the distance Ben ran. The three of them ran 21 km, how long was the run? [4]
Ben ran 5 times as far as Alex before he stopped.
David stopped 1 km before the finishing line and he ran 3 km less than twice the distance Ben ran. The three of them ran 21 km, how long was the run? [4]
A [ ] )
B [ ][ ][ ][ ][ ] ) 21 km
D [ ]< 3 > )
[ ]<1> Finishing line
2B [ ][ ][ ][ ][ ][ ][ ][ ][ ][ ]
16 u -- > 21 + 3 = 24
1 u -- > 24 ÷ 16 = 1.5
10 u -- > 10 x 1.5 = 15
15 – 3 + 1 = 13 km
The run was 13 km long.
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