The Commutative property: Decimal numbers

To make things simpler, we use the substitution property and arrange the exercise in the following manner:

$5.2+12.4-7.4+3.2+6.6=$

Keep in mind that the subtraction operation here gives us a whole number:

$12.4-7.4=5$

Now we obtain the exercise

$5.2+5+3.2+6.6=$

We solve the addition exercise:

$3.2+6.6=9.8$

And we obtain the exercise:

$5.2+5+9.8=$

We arrange the exercise using the substitution property to make fiding the solution simpler:

$5.2+9.8+5=$

We solve the exercise from left to right:

$5.2+9.8=15$

$15+5=20$

We first rewrite the decimal fraction in the form of a mixed fraction:

$5.25=5\frac{1}{4}$

We obtain the following exercise:

$5\frac{1}{4}\cdot\frac{2}{3}\cdot\frac{7}{21}=$

We write the mixed fraction as a simple fraction:

$5\frac{1}{4}=\frac{4\times5+1}{4}=\frac{20+1}{4}=\frac{21}{4}$

We obtain the following:

$\frac{21}{4}\cdot\frac{2}{3}\cdot\frac{7}{21}=$

We simplify the 21 and obtain:

$\frac{7}{4}\cdot\frac{2}{3}=\frac{14}{12}=\frac{12+2}{12}=1\frac{2}{12}=1\frac{1}{6}$