Divide both sides by 8.5 to get b on its own
68/8.5 = 8
So b = 8
Answer:
16
Step-by-step explanation:
two triangles are similar so if 5ft has 4ft shadow (whis is 1/4 of 20) 20ft should have 16ft
Answer:
13,15,17,19,21,23,25
Step-by-step explanation:
It goes up by 2 every term.
I'm going to decode the gibberish in the question and guess the equations are
Rachel:

Amber:

These equations tell us a few things not explicitly mentioned in the problem. Namely h is in feet, t is in seconds (because of the 16) and the building is 160 feet tall. h=0 corresponds to ground level. I made the constants of the equations the same because they're both on the twelfth floor. The difference between 36t and 50t reflect different vertical components of the velocity of the throw. The positive signs mean they each threw their book upwards. Air resistance is ignored.
So we need to solve two quadratic equations and compare the t values.




Only the plus sign gives a positive value of t, so that's our answer for Rachel:

For Amber we get




Again we choose the plus sign,

Rachel beat Amber by

Answer: 0.51 seconds