Answer:
They should use 1.2 gallons of yellow paint.
Explanation:
Given:
Julia and Rasheed are mixing yellow paint and blue paint to make green paint.
The mixture needs to be 60% blue paint and 40% yellow paint.
They need to make 3 gallons of the green paint.
Now, to find the quantity of yellow paint they should use.
As,
60% + 40% = 100%
So, we get the ratio of blue paint to yellow paint:
![60:40](https://img.qammunity.org/2021/formulas/mathematics/high-school/itd01kyekpy2zij9aabs1fi2loymuf4e3u.png)
=
![(60)/(40)](https://img.qammunity.org/2021/formulas/mathematics/high-school/84nh2mpkbjupc5b6zro8x2g5o5xvd2vjol.png)
=
![(3)/(2)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/810xodspel5mrswej0fay1vvz0sburw3kp.png)
=
![3:2.](https://img.qammunity.org/2021/formulas/mathematics/high-school/j4g9iycqcf7qvjy8iutz10euwhj2urxns4.png)
Thus, the ratio of blue paint : yellow paint is 3:2.
They need to make total 3 gallons of green paint.
Now, to get the quantity of yellow paint:
![(2)/(5)\ of\ 3\ gallons](https://img.qammunity.org/2021/formulas/mathematics/high-school/iv06tmg9tvzlmgii56azt4k92opy32qdsd.png)
![=(2)/(5) * 3](https://img.qammunity.org/2021/formulas/mathematics/high-school/4b3f0vosgnw2d7vrtd31u51si2vf30909w.png)
![=(6)/(5)](https://img.qammunity.org/2021/formulas/mathematics/high-school/mpu9nk4w8q0opu4s0zzdto9v281nmkxpo6.png)
![=1.2\ gallons.](https://img.qammunity.org/2021/formulas/mathematics/high-school/5ayalc11yg6vxv6k973lm4ff01ppxr1q85.png)
Therefore, they should use 1.2 gallons of yellow paint.