Answer:
a=28, b=-15
Step-by-step explanation:
[tex]Method\ by\ linear\ combinaisons\\\left\{\begin{array}{ccc|c|c|}2a+5b&=&-19&-1&3\\3a+5b&=&9&1&-2\\\end{array}\right.\\\\\\\left\{\begin{array}{ccc}a&=&28\\5b&=&-75\\\end{array}\right.\\\\\\\left\{\begin{array}{ccc}a&=&28\\b&=&-15\\\end{array}\right.\\[/tex]
