Cross multiplication

When a 7th grade math student came up to me and asked me about some mathematical problem help which was so simple. I was astonished and was wondering why didn't he know such simple mathematical problems. Well then he asked me to help in math, which i agreed.

Guys do you know what is cross multiplication?

Cross-multiplication is used mainly in the fraction and in proportional problems. The definition of cross multiplication is defined as from the given equation between two fractions, one can cross-multiply to simplify the equation or determine the value of a variable. The cross-multiplication is a process of arranging or solving for a variable in a given equation.

Look for an example below.

3/2 = 4/x

The rule three is,

x = (4*2) / 3

x = 8/3

I will come back until then keep smiling....