Answer:
(a) 25%
(b) 3:1
Explanation:
A shade of orange paint is made with 5 parts red paint and 15 parts yellow paint.
(a)
Total parts used in making orange paint=(5+15)+20 parts.
Number of parts of red paint used=5
Percent of paint is red=
![(Number of parts of red paint used)/(Total number of parts used)*100](https://img.qammunity.org/2020/formulas/mathematics/middle-school/7lq1y6wxy5chxo8wy7snc8rxqak7cwud3j.png)
=
![(5)/(20)*100](https://img.qammunity.org/2020/formulas/mathematics/middle-school/8i2qxs5fix1r8m4ofucnlbwb32uzx0heau.png)
=25%
Hence 25% of red paint was used to make orange paint.
(b)
The simplified ratio of yellow to red paint is:
![(15)/(5)=(3)/(1)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/ixox5a9mjkjzclh0ft1lvicifyjl4sknfh.png)
Hence, the ratio is: 3:1.