Associative Property: Only addition and subtraction

We solve the exercise from left to right, we place the addition exercise in parentheses and then subtract:

$(2+4)-3=$

$6-3=3$

We solve the exercise according to the order of operations.

We place the addition and subtraction exercises in parentheses in the following way to make it easier to solve:

$(2+6)-10+(30-2)=$

We solve the exercises in parentheses:

$8-10+28=$

We place the subtraction exercise in parentheses:

$(8-10)+28=$

$-2+28=26$

First, we place the subtraction exercise in parentheses, and then we add:

$(-3-2)+10=$

$-5+10=$

We use the substitution property to make solving the exercise easier:

$10-5=5$

According to the order of operations, we solve the exercise from left to right:

$3+2=5$

$5-11=-6$

According to the order of operations, we solve the exercise from left to right:

$4+5=9$

$9+1=10$

$10-3=7$

Given that in the exercise there is only one addition operation, the substitution property can be used:

$5+4+2a=$

We solve the exercise from left to right:

$5+4=9$

Now we obtain:

$2a+9$