Turn it into slope-intercept form.
2y = -x + 14
y = -x/2 + 7
The slope is -1/2.
Perpendicular lines have slopes that are opposite reciprocal, so the slope of the perpendicular line is 2.
The formula required to answer this is:

where A is the amount of the principal P after n compounding periods per year at r interest rate (as a decimal fraction).
Plugging in the given values, we get:

Rounding to the nearest dollar, we get $662.00. Therefore a is the best answer choice.
For #7 - part a: greatest common factor (GCF) is 5.
Part b: cross out everything BUT 10 & 20.
Total no. of buttons = 300 + 700 + 1000
+ 500 = 2500
Possibility for a person to pick a pink button = 300/2500 = (3/25)%
Amount of pink buttons she can expect her friends to pick = 50(3/25) = 6
She can expect to make 6 pink barrettes.
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