Start with the second equation and isolate 4b by multiplying both sides by 3c (4b)/(3c) = 1/7 4b = 3c/7 Now multiply both sides by 1/2 to get 4b*(1/2) = (3c/7)*(1/2) 2b = 3c/14
That will be plugged into the '2b' of the first equation a/(2b) = 3/5 a/(3c/14) = 3/5 (a/1) divided by (3c/14) = 3/5 (a/1)*(14/(3c)) = 3/5 (a*14)/(1*3c) = 3/5 (14a)/(3c) = 3/5 (a/c)*(14/3) = 3/5
The last step is to multiply both sides by 3/14 to isolate a/c (a/c)*(14/3) = 3/5 (a/c)*(14/3)*(3/14) = (3/5)*(3/14) a/c = (3*3)/(5*14) a/c = 9/70
So that's why the answer is choice B) 9/70
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An alternative way to get the answer is to first isolate 'a' in the first equation Use cross multiplication a/(2b) = 3/5 5a = 6b a = 6b/5 <-- call this equation (3)
Do the same for 'c' in the second equation (4b)/(3c) = 1/7 7*4b = 3c*1 28b = 3c 3c = 28b c = 28b/3 <-- call this equation (4)
