Question

5a-2b supra2a+b=1supra4 calculati a supra b

Answer 1

20a-8b=2a+b
18a=9b
a=9b\18=>a=1\2b  inlocuim in:
2a+b=4=>2x1\2b+b=4
2b\2+b=4aducem la acelasi numitor
2b\2+2b\2=4
4b\2=4
4b=8=>b=2 daca a=1\2b,atunci
a=1\2*2
a=2\2=>a=1 
a\b=1\2

Answer 2

$\frac{5a-2b}{2a+b} = \frac{1}{4}$

4*(5a-2b) = 1*(2a+b)
20a-8b = 2a+b
20a-2a = b+8b
18a=9b /:9
2a=b

$\frac{a}{b} = \frac{1}{2}$