If one third of t is 7 than t is equal to 21

It's a slope-intercept form where a slope = -1.5 and y-intercept = 3.
x - intercept: y = 0
Therefore we have the equation:
-1.5x + 3 = 0 |-3
-1.5x = -3 |:(-1.5)
x = 2
Answer: x-intercept = 2, y-intercept = 3
There were 80 questions on the test.
Answer:
P ( snowboard I ski) = 0.5714
Step-by-step explanation:
Conditional Probability
We use the conditional probability formula to solve this question. It is

In which
P(B|A) is the probability of event B happening, given that A happened.
is the probability of both A and B happening.
P(A) is the probability of A happening.
In this question:
Event A: Ski
Event B: Snowboard.
28 out of 120 students ski:
This means that 
16 out of 120 do both:
This means that 
P ( snowboard I ski)

So
P ( snowboard I ski) = 0.5714