# Problem solving

Enea and his friends, less than ten people in total, go to a restaurant with a fixed price menu: the price for a second course of meat is €11 while for a second course of fish €13. If Enea and his friends spent €107 on second courses, how many second courses of fish did they order?
5

2
9
4
7

Worked gold has 75% gold while the remaining part is made up of some metals which allow it to increase its rigidity and vary its colour. Tommaso’s jewelry is famous for green gold rings made with 12.5% ​​copper and 12.5% ​​silver. If Thomas has 12 g of silver, 28 g of copper and 60 g of gold in stock, how many grams of green gold can he make at most?
74
96
72
80
88

is there a time effective way to solve these questions?

hi

Question 1)

if they all chose fish 107/13=8,23
if they all chose meat 107/11=9,7
i’ll assume that 9 poeple had dinner since it’s a value between the two

13x+11(9-x)=107
2x=8
x=4

Question 2)

ratio gold : copper : silver = 75 : 12,5 : 12,5 = 6 : 1 : 1
we have 60g of gold so the amount of copper and silver needed follows the ratio
60 : 10 : 10
so the max we can make is 60+10+10=80 g of green gold with 2g leftover silver and 18g leftover copper

1 Like

Hi Juliette - could you explain how you get the (9-x) for Q1?

if there are 9 people total, and x people take fish, then 9-x people take meat