How many marbles at the start?
Sam had some marbles. He gave 1/3 of them to his friend Lucy. Then he lost 12 marbles on the way home. In the end, he had 16 marbles left.
How many marbles did Sam have at the start?
Word Problem
A bridge is built across a river. One quarter of the bridge is over the left bank of the river and one third of the bridge is over the right bank. The river is 120 m wide. How long is the bridge?
Let the number of marbles Sam had at the start be x.
ReplyDeleteHe gave away 1/3 of them:
That means he kept 2/3 of his marbles:
→ (2/3) × x
Then he lost 12 marbles:
→ (2/3)x - 12
We’re told he ended up with 16:
(2/3)x - 12 = 16
Now solve:
(2/3)x = 28
Multiply both sides by 3:
2x = 84
Divide by 2:
x = 42