For this case, the first thing we must do is define variables.
We have then:
x: number of $ 10 coins
y: number of $ 20 coins
We now write the system of equations that models the problem:
[tex] x + y = 50 [/tex]
[tex] 10x + 20y = 740 [/tex]
The graphical solution (see attached image) is given by the intersection of the equations.
We have then:
[tex] x = 26 [/tex]
[tex] y = 24 [/tex]
Answer:
Dave has:
26 $ 10 coins
24 $ 20 coins
