SOLUTION: solve for x in proportion 3 over x = 20 over 7 7 over 12 = x over 30 11 over 3 = x over 8 how do i solve these problems?

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Question 392816: solve for x in proportion
3 over x = 20 over 7
7 over 12 = x over 30
11 over 3 = x over 8
how do i solve these problems?
Found 2 solutions by richard1234, checkley79:
Answer by richard1234(7193) About Me  (Show Source):
You can put this solution on YOUR website!
For the first one, we have

3%2Fx+=+20%2F7

Cross multiply to obtain 20x+=+21 --> x+=+21%2F20

Use the same method for the other two problems.

Answer by checkley79(3341) About Me  (Show Source):
You can put this solution on YOUR website!
3 over x = 20 over 7
3/x=20/7 crosss multiply.
20x=3*7
20x=21
x=21/20 ans.
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7 over 12 = x over 30
7/12=x/30
12x=7*30
12x=210
x=210/12
x=17.5 ans.
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11 over 3 = x over 8
11/3=x/8
3x=11*8
3x=88
x=88/3
x=29.33 ans.