Problem Solving

VJesus12 wrote:A straight line has a slope of 1/2 and a y-intercept of -2. On this line, what is the x-coordinate of the point whose y-coordinate is 10?

A. (8)
B. (12)
C. (13)
D. (16)
E. (24)

Given this information, we can write the equation for the line in slope y-intercept form, y = mx + b, where m = the slope and b = the y-intercept

We're told that the slope is 1/2 and the y-intercept is -2
So, the equation of the line is: y = (1/2)x + (-2)
Simplify to get: y = (1/2)x - 2

What is the x-coordinate of the point whose y-coordinate is 10?
In other words, what does x equal when y = 10?
Take the equation of the line, y = (1/2)x - 2 and replace y with 10 to get: 10 = (1/2)x - 2 [now solve for x]
Add 2 to both sides: 12 = (1/2)x
Solve, x = 24

So, when y = 10, x = 24

Answer: E

Cheers,
Brent