Answer:
![-(2)/(5).](https://img.qammunity.org/2023/formulas/mathematics/college/99qrsfh7ntyi8v5c8ssl7et8n2cykz7ltp.png)
Explanation:
1) if to re-write the given equation into slope-interception form, then:
![y=(5)/(2)x-7;](https://img.qammunity.org/2023/formulas/mathematics/college/5bk39egqnt9zl8c0klfmg0jcv09ubf4eyy.png)
the slope of the given line is 5/2;
2) according to the rule of perpendicular, the required slope should be:
s*(5/2)=-1;
3) if to solve this equation (s*5/2=-1), then s=-2/5 or -0.4.