Chapter 3 Linear Systems and Matrices - 3.2 Solve Linear Systems Algebraically - 3.2 Exercises - Skill Practice - Page 165: 45

$$x=\frac{90}{31} , y=-\frac{67}{31}$$

Solving the equation using substitution, we find: $$\frac{7}{100}\left(\frac{21}{5}+\frac{3}{5}y\right)+\frac{1}{50}y=\frac{4}{25} \\ y=-\frac{67}{31}$$ Thus: $$x=\frac{21}{5}+\frac{3}{5}\left(-\frac{67}{31}\right)=\frac{90}{31}$$