To find the readership need to increase to reach his goal, we can do a simple deductions.
By dedcuting the current readership (2.8m) from the original readership (3.5m), we can find his goal:
3.5-2.8
=1.3 million
Alternately,we can set an equation with one unknown.
Let y be the million he need to increase:
y+2.8=3.5
y+2.8-2.8=3.5-2.8
y=3.5-2.8
y=1.3 million
Therefore, the answer is 1.3 million.
Hope it helps!