Because of the commutative property of multiplication, it is true that 3 4 × 4 = 4 × 3 4 . However, these expressions can be calculated in different ways even though the solutions will be the same. Below, show two different ways of solving this problem. First, show how 3 4 × 4 can be solved using repeated addition.

Step-by-step explanation:

We know that when we multiply a by b it means add a plus a plus a in b times

34× 3 means 34 plus 34 plus 34 three times

34×3=34+34+34

34+34+34 =136

Second method

Since multiplication is commutative

a*b=b*a

Then, 34×4=4×34

So let do 4×34

4×34 means 4 plus 4 plus 4 thirty four times

4×34= 4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4+4=136.

Both are correct.

step-by-step explanation: a reaction is first order. if the initial reactant concentration is 0.0200 m, and 25.0 days later the concentration is 6.25 x 10-4 m, then its half-life is: