Answers

2016-07-22T17:41:18+08:00
I. Simply multiply the extremes and means. The answers should be equal.
1. 12 × 4 ≠ 15 × 5; therefore, the answer is no.
2. 5 × 9 ≠ 8 × 6; therefore, the answer is no. (In this case, just perform cross multiplication)
3. 6 × 10 ≠ 13 × 26; therefore, the answer is no.
4. 7 × 24 = 12 × 14; therefore, the answer is yes.
5. 9 
× 18 ≠ 15 × 30; therefore, the answer is no.

II. Simply cross-multiply.
1.)\\3*15=5*n\\ \frac{3*15}{5}=n \\ \frac{45}{5}=n\\ \frac{45}{5} =9\\ 2.)\\3*8=2*n\\ \frac{3*8}{2}=n \\ \frac{24}{2}=n\\ \frac{24}{2}=12\\3.)\\5*21=15*n\\ \frac{5*21}{15}=n \\ \frac{105}{15}=n\\ \frac{105}{15}=7
\\4.)\\
25*18=75*n\\ \frac{25*18}{75}=n \\ \frac{450}{75}=n\\ \frac{450}{75}=6
\\5.)\\
5*24=6*n\\ \frac{5*24}{6}=n \\ \frac{120}{6}=n\\ \frac{120}{6}=20

Sorry, I wasn't able (or let's just say, I just don't want) to answer all of them. Try answer them by yourself :)
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