Răspuns:
Explicație pas cu pas:
[tex]3\frac{4a}{90}<\frac{173}{50},~\frac{3*90+40+a}{90} <\frac{173}{50}~|*10,~\frac{310+a}{9}<\frac{173}{5},~5*(310+a)<9*173,~1550+5a<1557, ~5a<1557-1550,~5*a<7,~deci~a=0~sau~a=1.[/tex]
