Answer:
![y = 6](https://img.qammunity.org/2021/formulas/mathematics/middle-school/y58czv7tibr01pkeudee9cxj34dnfcjye5.png)
![RS = 38](https://img.qammunity.org/2021/formulas/mathematics/high-school/srjtxbl558d3b275f42mjjeezarnuxeksp.png)
![ST = 39](https://img.qammunity.org/2021/formulas/mathematics/high-school/r6hg7lpzsmw8c01uqfu7i3ve77std0w5ln.png)
![RT = 77](https://img.qammunity.org/2021/formulas/mathematics/high-school/5i8kpumrssxpr9f0fkvpzja67tv5mlx66i.png)
Explanation:
Given:
![RS = 6y +2](https://img.qammunity.org/2021/formulas/mathematics/high-school/9x29bp3yzftzzy30rrm14jdcdb0ey494t2.png)
![ST=5y + 9](https://img.qammunity.org/2021/formulas/mathematics/high-school/uvxqsvwc4la4yfd2ah0inwo2vrvoogapnt.png)
![RT= 13y - 1](https://img.qammunity.org/2021/formulas/mathematics/high-school/8e1vg0adgzxtsuvx3hd43bao4r0dx83ikh.png)
Solving (a): The value of y
From the given parameters, we understand that
![RT = RS + ST](https://img.qammunity.org/2021/formulas/mathematics/high-school/ubv3viol9r1vfoh2wi895y8ya8y05mzvfl.png)
Substitute values for RS, ST and RT
![13y - 1 = 6y + 2 + 5y + 9](https://img.qammunity.org/2021/formulas/mathematics/high-school/pi31clp6vdad4zly2rpaujjwd21a5ru0y0.png)
Collect Like Terms
![13y - 6y - 5y = 1 + 2 + 9](https://img.qammunity.org/2021/formulas/mathematics/high-school/upyemg5z5y5bt72v76vhdz760taiaxy3z8.png)
![2y = 12](https://img.qammunity.org/2021/formulas/spanish/high-school/o9tkpv5hsgtv8cbfd5l21v9cbyt9tdbqfi.png)
Divide both sides by 2
![y = (12)/(2)](https://img.qammunity.org/2021/formulas/spanish/high-school/zrczzi3s0826oyofug6bvsim87tvxyq1sw.png)
![y = 6](https://img.qammunity.org/2021/formulas/mathematics/middle-school/y58czv7tibr01pkeudee9cxj34dnfcjye5.png)
Solving (b):
The value of RS
Substitute 6 for y in
![RS = 6y +2](https://img.qammunity.org/2021/formulas/mathematics/high-school/9x29bp3yzftzzy30rrm14jdcdb0ey494t2.png)
![RS = 6 * 6 + 2](https://img.qammunity.org/2021/formulas/mathematics/high-school/65y29vij4qqe7k2ahema0wz977zzn84b08.png)
![RS = 36 + 2](https://img.qammunity.org/2021/formulas/mathematics/high-school/hdqpp9g4swzaumtzzr9fzv9ghlor71bere.png)
![RS = 38](https://img.qammunity.org/2021/formulas/mathematics/high-school/srjtxbl558d3b275f42mjjeezarnuxeksp.png)
The value of ST
Substitute 6 for y in
![ST=5y + 9](https://img.qammunity.org/2021/formulas/mathematics/high-school/uvxqsvwc4la4yfd2ah0inwo2vrvoogapnt.png)
![ST = 5 * 6 + 9](https://img.qammunity.org/2021/formulas/mathematics/high-school/wd4hacvmbwu7twqds8wyrfk1qsvy3litt9.png)
![ST = 30 + 9](https://img.qammunity.org/2021/formulas/mathematics/high-school/5sx1qeu8oo5ude5hm4zkmhen7nv9ppesfa.png)
![ST = 39](https://img.qammunity.org/2021/formulas/mathematics/high-school/r6hg7lpzsmw8c01uqfu7i3ve77std0w5ln.png)
The value of ST
Substitute 6 for y in
![RT= 13y - 1](https://img.qammunity.org/2021/formulas/mathematics/high-school/8e1vg0adgzxtsuvx3hd43bao4r0dx83ikh.png)
![RT = 13 * 6 - 1](https://img.qammunity.org/2021/formulas/mathematics/high-school/ab0mnc3s8yjeh1y3slyk7bs68a9c9xg5hq.png)
![RT = 78 - 1](https://img.qammunity.org/2021/formulas/mathematics/high-school/mgt08fuflpz6wuo7iuw2tv5uox5ewa1p3l.png)
![RT = 77](https://img.qammunity.org/2021/formulas/mathematics/high-school/5i8kpumrssxpr9f0fkvpzja67tv5mlx66i.png)