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

Write and solve an equation of proportions:

4/5 ton 5/6 bridge

=

x 1 bridge

Then (4/5) * (1 bridge) = (5/6 bridge)x.

Solve this for x by mult. both sides of the equation by 6/5:

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

24/25 tons of concrete are needed to complete the entire bridge.

i just took the test, the correct answer is .. 31.5 in.