Find the original number
I think of a number. I multiply it by 4, then subtract 6. The result is the same as if I had doubled the number and added 10.
What was the number I originally thought of?
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 be x.
ReplyDeleteAccording to the question:
Multiply by 4, then subtract 6:
→ 4x - 6
Double the number, then add 10:
→ 2x + 10
Set them equal:
4x - 6 = 2x + 10
Now solve:
4x - 2x = 10 + 6
2x = 16
x = 8