Question

a/8.4=20/6

Answer 1

First I'll write it out the right way.

Answer 2

\[\frac{ a }{ 8.4 }=\frac{ 20 }{ 6 }\]

Answer 3

First we'll cross multiply the numbers.

Answer 4

\[a \times6=6a\]\[20\times8.4=168\]Do you see how cross multiplying works?

Answer 5

yup

Answer 6

Good, now we have 6a=168

Answer 7

To undo the multiplication of "a", we divide. We'll divide both sides so that the proportion stays equal.

Answer 8

\[6a \div 6=a\]\[168\div6=28\]

Answer 9

Do you see how I divided to get the "a" alone, and understand why we have to do both sides.

Answer 10

@changedman1988?

Answer 11

Well, I hope you understand. So, the final answer is:
a=28

Answer 12

\[\frac{a}{8.4}=\frac{20}{6}\]\[8.4\times\frac{a}{8.4}=\frac{20}{6}\times 8.4\]\[\cancel{8.4}\times\frac{a}{\cancel{8.4}}=\frac{20}{6}\times 8.4\]\[a=\frac{20}{6}\times 8.4\]\[a=28\]