Ta có: \(\dfrac{3}{x} = \dfrac{y}{{35}} = \dfrac{{ - 36}}{{84}}\)
mà \(\dfrac{{ - 36}}{{84}} = \dfrac{{ - 36:12}}{{84:12}} = - \dfrac{3}{7}\)
Do đó
+) \(\dfrac{3}{x} = \dfrac{{ - 3}}{7}\), suy ra \(x.\left( { - 3} \right) = 3.7\) hay \(x = 21:\left( { - 3} \right) = - 7\)
+) \(\dfrac{y}{{35}} = \dfrac{{ - 3}}{7}\), suy ra \(7y = 35.\left( { - 3} \right)\) hay \(y = - 105:7 = - 15\)
Đáp số: \(x = - 7;y = - 15\)
