(1) Riješite sustav jednadžbi metodom supstitucije:

 (a)  \( \text{4}x + \text{8}y = \text{3} \)  \( y = \text{-1} \)

 (b)  \( \text{9}x - \text{6}y = \text{-1} \)  \( x = \text{3} \)

 (c)  \( x - \text{8}y = \text{-8} \)  \( x + \text{4}y = \text{7} \)

 (d)  \( \text{6}x + y = \text{-9} \)  \( \text{5}x + y = \text{0} \)

(2) Riješite sustav jednadžbi metodom zbrajanja:

 (a)  \( \text{3}x - \text{6}y = \text{9} \)  \( \text{-7}x + \text{3}y = \text{8} \)

 (b)  \( \text{14}x - \text{15}y = \text{24} \)  \( \text{10}x + \text{5}y = \text{-7} \)

 (c)  \( \text{4}x - \text{8}y = \text{3} \)  \( \text{6}y = \text{-6} \)

 (d)  \( \text{-7}x + \text{8}y = \text{4} \)  \( \text{3}x = \text{10} \)

 (e)  \( \text{2}x + y = \text{14} \)  \( \text{7}x - y = \text{10} \)

 (f)  \( \text{9}x - \text{6}y = \text{10} \)  \( \text{5}x + \text{2}y = \text{10} \)

 (g)  \( \text{4}x - \text{2}y = \text{25} \)  \( \text{2}x + \text{8}y = \text{18} \)

 (h)  \( \text{5}x + \text{2}y = \text{16} \)  \( \text{5}x - \text{2}y = \text{2} \)

(3) Pomnožite jednu od jednadžbi sustava s -7 i riješite sustav metodom zbrajanja:

 (a)  \( \text{7}x + y = \text{-9} \)  \( \text{9}x + y = \text{2} \)

 (b)  \( x + \text{10}y = \text{2} \)  \( \text{3}x + \text{6}y = \text{10} \)

 (c)  \( \text{-10}x + \text{5}y = \text{1} \)  \( \text{7}x + \text{7}y = \text{57} \)

 (d)  \( x + \text{5}y = \text{-15} \)  \( \text{4}x + \text{9}y = \text{-2} \)

(4) Odredite kojim brojem je prikladno pomnožiti jednu od jednadžbi sustava i riješite sustav metodom zbrajanja:

 (a)  \( \text{2}x + \text{2}y = \text{16} \)  \( \text{2}x - y = \text{5} \)

 (b)  \( \text{5}x + y = \text{1} \)  \( \text{7}x - \text{9}y = \text{-9} \)