Answer:
1021
Step-by-step explanation:
1+1=2 and it needs to add up to 4 so you add in another 2 in the only place left for it to go which is in the tens place because the first and last number have to be the same and 0 has to go in the hundreds place.
If u use the app photomath it will give u answer with the steps too
X = 5
So 3x = 3(5) = 15
3x = 15