Answer:
DP = 56 [kg*m/s]
Step-by-step explanation:
We know that momentum is defined by the product of mass by Velocity. In this way by means of the following equation, we can calculate the impulse.

where:
P = momentum [kg*m/s]
m = mass [kg]
v = velocity [m/s]
Now replacing:
![P=8*9\\P=72[kg*m/s]](https://img.qammunity.org/2022/formulas/physics/high-school/q17sn99vpit98gtgcrzmdf42u64mdgalys.png)
And after the ball hits the wall:
![P_(2)=8*2\\P_(2)=16[kg*m/s]](https://img.qammunity.org/2022/formulas/physics/high-school/wt2isp19fke22xh3i7msxexa2hp9qqujlm.png)
The change in momentum is equal to:
![DP=72-16\\DP = 56 [kg*m/s]](https://img.qammunity.org/2022/formulas/physics/high-school/k3jbl3r8u5erfi3t8rvwml6p430vhkzxa6.png)