Question

va rog ajutatima !
pentru 3 mingi de fotbal si 4 mingi de tenis s-au platit 182 lei.pentru 7 mingi de fotbal si 4 mingi de tenis s-au platit 382lei.cat costa o minge de fotbal?dar una de tenis?

Answer 1

$\left \{ {{3f+4t=182} \ \ \ |(-1)\atop {7f+4t=382}} \right. \\\\\\ \underline{\left \{ {{-3f-4t=-182} \atop {7f+4t=382}} \right. } \\4f \ /=200 \ \ \ |:4 \\\\ \boxed{f=50 \ mingi \ fotbal} \\\\\\ 4t=182-3f \\\\ 4t=182-3*50 \\\\ 4t=182-150 \\\\ 4t=32 \ \ \ |:4 \\\\ \boxed{t=8 \ mingi \ tenis}$

3f+4t=182
7f+4t=382

4t=182-3f
4t=382-7f

De aici rezulta ca cele 2 ecuatii sunt egale.

182-3f=382-7f

382-182= 7f-3f

200=4f

f=200:4

f=50 mingi de fotbal

4t=182-3f
4t=182- 3 x 50
4t=182- 150
4t=32
t=32:4

t=8 mingi tenis