Answer:
5 weeks.
Step-by-step explanation:
We have $60, and we're saving an additional $5 each week:
[tex]60+5w[/tex]
Our brother has $45, and is saving an additional $8 each week:
[tex]45+8w[/tex]
Let's set up an equation:
[tex]60+5w=45+8w[/tex]
We had to set these two expressions equal to each other because our end result should be equal.
Subtract [tex]60[/tex] from both sides of the equation:
[tex]5w=-15+8w[/tex]
Subtract [tex]8w[/tex] from both sides of the equation:
[tex]-3w=-15[/tex]
Divide by the coefficient of [tex]w[/tex], which is [tex]-3[/tex]:
[tex]w=5[/tex]
Check your work:
You can check your work with substitution. Take the initial equation and substitute [tex]w[/tex] with [tex]5[/tex]:
[tex]60+5(5)=45+8(5)[/tex]
Simplify:
[tex]85=85[/tex] Â
It checks out!