For this case the mapping diagram would be:
We have the following points given:
(1,8), (3,6) and (5,4)
Since we have a line pattern we can find the equation with this formula:
![y=mx+b](https://img.qammunity.org/2023/formulas/mathematics/high-school/smsb8cbft03lwblmi49nf2l6jby2ofxzws.png)
Where m is the slope and b the intercept:
![m=(8-6)/(1-3)=-2](https://img.qammunity.org/2023/formulas/mathematics/college/yh6qwwn3pji1ponki7gwz9fkj2y9lflo16.png)
And for the intercept we got:
![8=-2(1)+b](https://img.qammunity.org/2023/formulas/mathematics/college/c8vma9kbrgn6t2bfxgx5u4ov3seuxp41am.png)
And solving for b we got:
![b=10](https://img.qammunity.org/2023/formulas/mathematics/college/shd1chkkxww9lmteq8a2k07mouirv8gs1t.png)
And the equation would be given by:
![y=-2x+10](https://img.qammunity.org/2023/formulas/mathematics/college/zecpy42498xlvarlfu1f30apd1i8dx2sji.png)