Answer:
2x + 2.9 = 30.6
Step-by-step explanation:
We are to represent the unknown number that Mark thinks of with x
If Mark doubles this unknown number, he multiplies it by 2 and the unknown number becomes - 2x
He then adds 2.9
The equation becomes 2x + 2.9
The answer of the above equation is 30.6
This gives : 2x + 2.9 = 30.6
