Answer:
40/9
Step-by-step explanation:
Use the work formula, 
+ 
= 
, where A is the amount of time it takes one person, B is the amount of time it takes another person, and T is the time it takes for them to work together.
Plug in the times for David and Alex alone:
+ 
=
Find the least common denominator, which is 40.
+ 
=
=
Cross multiply and solve for T:
9T = 40
T = 40/9
So, if they worked together, it would take them 40/9 hours
I would say 8 but im gonna say 6 cause im a rebel
To solve this problem you must apply the proccedure shown below:
1. You have that:
- He sales 13 gold rings and 18 silver rings in 9405 euros.
<span> - The cost of the silver ring is three times the cost of the gold ring.
2. Keeping the information above on mind, you have the following system of equations:
x: the gold ring.
y: the silver ring.
x+y=</span>9405
<span> x=3y
3. Then, you have:
(3y)+y=9405
y=9405/4
y=2351.23 euros
x=3y
x=3(</span>2351.23)
<span> x=7053.75 euros
The answer is:
- Gold ring=</span>7053.75 euros
- Silver ring=2351.23 euros<span>
</span>
