The students of class A, class B and class C planted 66 trees. The trees planted in class A were twice as many as those planted in class B. the ratio of trees planted in class C and class B was 2:3 How many trees to plant each? (cubic equation)

A. B. C
a+b+c=66
a=2b
c/b=2/3
A = 36, B = 18, C = 12

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