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# 9 Math problems: Solve each proportion from pages 371, 372 and 378

Page 371 & 372

Solve each proportion

# 28. 9 3
--- = ---
X 2

# 31. 5 3
--- = ----
9 x

# 39. a a + 3
------ = --------
A + 1 a

# 41. m - 1 m - 3
----------- = ------------
M - 2 m + 4

# 45 Voting. If 220 out of 500 voters surveyed said that they would vote for the incumbent, then how many votes could the incumbent expect out of the 400,000 voters in the state?

# 55. Miles and hours. Of Alonzo travels 230 miles in 30 minutes, then how many miles dose he travel in 7 hours?

Page 378.

Solve each formula for the indicated variable .

# 14. mv^2
F = -------- for r
R

# 16. 1 1 1
--- = --- + ---- for r
R R/1 R/2

# 21. 4
V = -- ttr^2h for h
3

# 22. S - 2 ttr^2
H = -------------- for S
2 ttr

#### Solution Preview

# 28.
9/x = 3/2
The way you solve these types of equations is to "cross multiple."
(9)(2) = 3x
18=3x
Now you divide each side by 3 to get x by itself.
6=x

# 31.
5/9 = 3/x
You solve this one exactly like we solved the one above. Cross multiply and then divide by the number next to the x.
5x=(3)(9)
5x=27
x=27/5

# 39.
a/(a+1) = (a + 3)/a
Here we start off by cross multiplying.
a^2 ...

#### Solution Summary

The math problems of proportion and indicated variable are clearly solved in the response.

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