Answer:
x = 6.7
Explanation:
We know that 3.5 + x = 10.2, so if we do inverse operations we can find out the value of x.
10.2 - 3.5 = 6.7
we can check our work by substituing it back in the equation for x
6.7 + 3.5 = 10.2
so now we know that x = 6.7. I hope this helps :)