Salut.
a × 0,25 = b × 1,25
[tex]\displaystyle{a \times \frac{25}{100}=b \times \frac{125}{100}}[/tex]
[tex]\displaystyle{a \times \frac{1}{4}=b \times \frac{5}{4}}[/tex]
[tex]\displaystyle{\frac{a}{4}=\frac{5b}{4}}[/tex]
a = 5b
a + b = 13
5b + b = 13
6b = 13
b = 13 ÷ 6
[tex]\boxed{b=\frac{13}{6}}[/tex]
a = 13 - b
[tex]\displaystyle{a = ^{6)}\frac{13}{1} -\frac{13}{6} }[/tex]
[tex]\displaystyle{a = \frac{78}{6}-\frac{13}{6} }[/tex]
[tex]\displaystyle{a = \frac{78-13}{6} }[/tex]
[tex]\boxed{a=\frac{65}{6}}[/tex]
- Lumberjack25
