Question

Proportions...

Answer 1

\[\frac{ x }{ 3 } = \frac{ x+4 }{ 5 }\]

Answer 2

Please explain how to do it :(

Answer 3

Cross multiplication! Multiply the numerator of the first fraction with the denominator of the second fraction, and multiple the denominator of the first fraction with the numerator of the second. Then set those values equal to each other and solve for a variable.
e.g.

\[if \frac{ a }{ b } = \frac{ c }{ d } \]
then \[ad = bc\]

Then you can solve for whatever you like. solving for a would be
\[ad \div d = bc \div d\]
\[a = \frac{ bc }{ d }\]

Answer 4

I think I got it :)