mcetner

Step 1: define variables:  let x = the number of trips the 10 ton truck makes, and let y = the number of trips the 12 ton truck makes. Step 2: write equations:  total number of trips: x + y = 20. ...

Since you know the probability of drawing a red ball is 7/15, and you know the amount of balls in the box is 30, then you can make a proportion: probability 7/15 = x/30.  Solve for x by...

The easiest way to figure out this type of question without being confused is to use dimensional analysis.  That means when you divide, the units that you don't want will cancel, and what you want...

Another way to answer this question is that you know any linear function can always be written y = mx + b, where m is the slope. Find m first, (4 - 3)/(2 - -1)=1/3. Then plug in one point to solve...

The slope of the tangent line means derivative.  So, take the derivative of y = cosx - 2, and get dy/dx = -sinx.  Evaluate at pi/2, and -sin(pi/2) = -1.  So the slope of the tangent line at that...