单选题If 5a+3b = 35 and a/b = 2/5, what is the value of a?A14/5B7/2C5D7E9
单选题
If 5a+3b = 35 and a/b = 2/5, what is the value of a?
A
14/5
B
7/2
C
5
D
7
E
9
参考解析
解析:
In the equation a/b = 2/5, cross-multiplying gives 5a = 2b. Since 5a+3b = 35 and 5a = 2b, then 2b+3b = 35, b=7. Since 5a = 2b = 2(7) = 14, a = 14/5
In the equation a/b = 2/5, cross-multiplying gives 5a = 2b. Since 5a+3b = 35 and 5a = 2b, then 2b+3b = 35, b=7. Since 5a = 2b = 2(7) = 14, a = 14/5
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