Answer:
10 weeks
Step-by-step explanation:
Let's set an equation for you and your brother.
You have $90 plus $18 for every week you save (x).
90+18x
And your brother has $120 plus $15 dollars per week that he saves (x)
120+15x
You want to have the sum of the money equal so combine the two concluded statements
90+18x=120+15x
Arrange them so that you have like terms on each side
90+18x-15x=12+15x-15x
90+3x=120
90-90+3x=120-90
3x=30
x=10
"x" is our number of weeks you and your brother save so the answer is 10 weeks
Just to be sure you can use our equation and plug 10 for every time you see x to make sure our answer is right.
y = mx + b, where m = slope, and b = y-intercept.
Since you are not given the y-intercept, you have to solve for it through the equation, y = (4/5)x (which is the slope you are given) + b, and replace x and y with values given, which are (-5,-3)
y = (4/5)x + b
-3 = (4/5)(-5) + b
-3 = -4 + b
1 = b
Then replace b in the first equation to get the answer
y = (4/5)x + 1
