If 4/5 ton of concrete cover is 5/6 of a bridge how many tons of concrete are required to cover the entire bridge

Here, the easiest method is using the rule of three:
Cover the entire bridge means to cover 6/6 of the bridge.
Let x be the tons needed to cover the entire bridge.

4/5 --> 5/6
x -- > 6/6

x = (6/6 * 4/5) / 5/6
x= (4/5) / (5/6)

Dividing 2 fractions is equal to the multiplication of the first fraction by the inverse of the second:
x= (4/5) * (6/5)
x= 24/25

So 24/25 ton of concrete is needed to cover the entire bridge.

Hope this Helps! :)

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