Answer: 28
Explanation:
The answer is 28. Take one side for example, we'll do the bottom one. On the left it is 10, and on the right it is 35. To make them equivalent, you must multiply something by 10 to get 35.
Now 35 divided by 10 is 3.5 ( just move the decimal in front of one of the digits ). ( we divide because the opposite of multiplication is division, and the result will be the answer that we can multiply it by )
To make sure this is right and check our answer, we can take 12 and multiply it by 3.5, also giving us 42.
Then finally for the missing side, multiply 8 by 3.5, which gives us 28
Hope this all helps and have a great day!!! <33