{a;b} d p {5;3}=> [tex]\frac{a}{5} =\frac{b}{3} =k => a=5k ;b=3k[/tex]
2a+b= 2*5k + 3k = 13k
a) 3b-a = 3*3k - 5k = 9k-5k = 4k
b) a+b = 160 => 5k +3k = 160
8k = 160 =>k = [tex]\frac{160}{8} = 20[/tex] => a= 5k = 5*20 = 100
b = 3k= 3* 20 = 60
c) a*b=135
5k*3k=135
[tex]15*k^{2} =135 / :15\\k^{2} =9 => k=\sqrt{9} = 3 => a=5k=5*3=15 ; b=3k=3*3=9[/tex]