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m_a_m_a [10]
2 years ago
8

1. Chelsea can paint a fence in 9 hours, and Greg can paint the same fence in 7 hours. How long does it take them to paint the f

ence if they work together? Round to the nearest tenth.
2. Tom left the mall and drove south. George left 2 hours later driving 36 mph faster to catch up with Tom. After 3 hours, he caught up with Tom. Find Tom’s average speed


72 mph


54 mph


90 mph


36 mph
Mathematics
1 answer:
Leto [7]2 years ago
7 0

Answer:

  1. 3.9 hours
  2. 90 mph

Step-by-step explanation:

<h3>1.</h3>

The sum of the rates of painting, in fences per hour, is ...

  1/9 + 1/7 = (9+7)/63 . . . . fences per hour

The total rate in hours per fence is the inverse of that:

  63/16 = 3 15/16 ≈ 3.9 . . . hours to paint the fence

__

<h3>2.</h3>

The relevant relationship is ...

  distance = speed × time

Let t represent Tom's speed in miles per hour. Then George's speed is (t-36). They both have traveled the same total distance at the point where Tom catches up.

  (2+3)(t-36) = 3t

  2t = 180 . . . . . . . add 180-3t

  t = 90 . . . . . . divide by 2

Tom's average speed is 90 miles per hour.

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Find the area of the triangle with the given measurements. Round the solution to the nearest hundredth if necessary. B = 67°, a
kvasek [131]

Among many other formulas, the area of a triangle is


S = \frac 1 2 a c \sin B


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Bonus. Here's a formula for the area S of a triangle your teacher doesn't know:


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7 0
3 years ago
Make B the subject of the relation : 1/a is equal to 1/b + c​
stealth61 [152]

Answer:

By making ‘a’ the subject, I believe you mean isolate the variable ‘a’.

1/a - 1/b = 1/c : add 1/b to both sides

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1/a = (1/b)(c/c) + (1/c)(b/b) : simplify

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This will not work if c = -b, because then you would be dividing by zero.

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Step-by-step explanation:

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3 years ago
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