Answer:
? = 7x
Step-by-step explanation:
Lets simplify the equation first;
5x - 20 + ? = -20 + 12x
=> So now, we have to make the equation on the left equation congruent to the right equation:
It we already have -20 common on both sides, but we need to find out, what added by 5x gives us 12x,
=> So we can let the number we have to find out be y, and say:
5x + y = 12x
=> y = 12x - 5x
=> y = 7x
Therefore, ? = 7x
Hope this helps!
