39 it's an arithmetic sequence in which the common difference is +7
Answer: x= 5
Step-by-step explanation:
Plug the second equation into the first equation’s y.
3x-2(-2x+7)=21
Then use distribution
3x+4x-14=21
Add 4x and 3x
7x-14=21
Then add 14 to both sides
7x=35
Divide by 7 to get x
35/7=5
x=5
Answer: 
Step-by-step explanation:
For this exercise it is important to remember the multiplication of signs. Notice that:

In this case you have the following expression given in the exercise:

Then you can follow the steps shown below in order to solve it:
Step 1: You must solve the subtraction of the numbers 0,65 and 3,21. Then:

Step 2: Now you must find the product of the decimal numbers above. In order to do that you must multiply the numbers.
(As you can notice, both are negative, therefore you know that the product will be positive).
Then, you get that the result is the following:
