Answer:
Sue's percentage profit = 9% on each tin of green paint she sells.
Step-by-step explanation:
Litres of green paints mixed = 50 litres
Ratio of litres of yellow paint and litres of blue paint = 1:4.
To determine the litres of yellow paint, we say:
![yellow \: paint = (1)/(4) * 50 = 10 \: litres](https://img.qammunity.org/2021/formulas/mathematics/high-school/aanh5b639wbt33cicke8x8f1t1r1d1xqin.png)
To determine the litres of blue paint, we say:
![blue \: paint = (4)/(5) * 50 = 40 \: litres](https://img.qammunity.org/2021/formulas/mathematics/high-school/4dzi3siilottoi3eednkejq93b6i22u7os.png)
Since yellow paint is sold in 5 litres per tin and each tin cost £38; she has 10 litres of yellow paint in all. That implies that she has 10/5 = 2 tin of yellow paint. If one tin cost £38; 2 tin cost 2 × £38 = £76
Similarly,
Since blue paint is sold in 10 litres per tin and each tin cost £58; she has 40 litres of blue paint in all. That implies that she has 40/10 = 4 tin of blue paint. If one tin cost £58; 4 tin cost 4 × £58 = £232
Total cost of yellow and blue paints = £232 + £76
= £308
Since Sue sells all the green paint she makes in 10 litre tins at £89.32 per tin and she has 50 litres in all; we say: 50/10 litres = 5 tins = 5 × £89.32 = £446.60.
Thus, selling price of the green paint = £446.60
![profit \: \% = (selling \: price - cost \: price)/(cost \: price) * (100)/(1)](https://img.qammunity.org/2021/formulas/mathematics/high-school/pwkuh4p49031dvwnl2azlyrk3ca73t5zhp.png)
![profit \: \% = (446.60 - 308)/(308) * (100)/(1)](https://img.qammunity.org/2021/formulas/mathematics/high-school/jful5v51andpe9lh9b8muafige2kbndxuu.png)
![profit \: \% = (138.60)/(308) * (100)/(1)](https://img.qammunity.org/2021/formulas/mathematics/high-school/zgxnsxlpaomrkg7p57xt19njxg6sia2j4l.png)
![profit \: \% = 0.45 * 100](https://img.qammunity.org/2021/formulas/mathematics/high-school/q216f4mi06adxeh38g22042hnuwbm5xjth.png)
![profit \: \% = 45\%](https://img.qammunity.org/2021/formulas/mathematics/high-school/x2nc324uhd2sabfc9p37xpxmibt018wda0.png)
Sue's percentage profit for selling all the tins of green paint is 45%, having sold 5 tins. Therefore, Sue's percentage profit for selling each of the paint will be:
![profit \: \% \: on \: each \: green \: tin = (45)/(5) = 9\%](https://img.qammunity.org/2021/formulas/mathematics/high-school/gqh11kwdzg5cwjo05kb86daaqvk6ex5ra2.png)
Hence, Sue's percentage profit for selling each tin of green paint is 9%.
Proof
9% × 5 tins of green paint = 45%