Question

AB:BC is 3:4. Solve for x.

A.11
B.14
C.120
D.140

Answer 1

You are given this, right?

\(\dfrac{AB}{BC} = \dfrac{3}{4} \)

Answer 2

right..

Answer 3

Now replace AB and BC with the lengths given in the figure.
What do you get?

Answer 4

\(\dfrac{90}{10x-20} = \dfrac{3}{4}\)

Ok?

Answer 5

oh okay

Answer 6

-20 is not the length of BC. The entire expression 10x - 20 is.
See my equation above?

Answer 7

Now we solve that equation.

Answer 8

When you have a fraction equal to a fraction, you can cross multiply.