Answer: $4.615 is the dollar value of incremental benefit.
Explanation:
10% increase in abatement A would be equal to the marginal social benefit.
0.1[tex]\times[/tex]A = 120 - 2.5A
2.6[tex]\times[/tex]A=120
A=[tex]\frac{120}{2.6}[/tex]
A = 46.15
Incremental benefit MSB = 120 - 2.5[tex]\times[/tex]46.15 =$4.615
$4.615 is the dollar value of incremental benefit.