The required numbers are 6 and 3
Solution: Assume the required numbers are a and b,
Given that the sum of two numbers is nine that is,
![a+b=9\rightarrow(1)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/veo1phba22nmm224e9ehzh67ko52fai509.png)
One number is three more than the other that is,
![a=b+3\rightarrow(2)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/xwi933b53fcygsblbuirr0nsimzp88d013.png)
On substituting (2) in (1) we get,
![\Rightarrow b+3+b=9\rightarrow 2b+3=9](https://img.qammunity.org/2020/formulas/mathematics/middle-school/4y1c96b7ml8mpft6vmlw0s0rpaszeevc6s.png)
On grouping the similar terms we get,
![\Rightarrow 2b=9-3 \rightarrow 2b=6 \rightarrow](https://img.qammunity.org/2020/formulas/mathematics/middle-school/6z4lvz797rv2l3mub2j5c21thj9sjpnsbj.png)
![\Rightarrow b=(6)/(2)\rightarrow b=3 \rightarrow (3)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/cjnglliqrxf0rb0ip28n7hsbbq2532wglt.png)
On substituting (3) in (1) we get,
![a+3=9\rightarrow a=9-3\rightarrow a=6](https://img.qammunity.org/2020/formulas/mathematics/middle-school/4tbxkevq5loqlw8gtcb1j2usfp8g03jx0u.png)
Therefore, the number are 6 and 3.