2*(500-у/3)=820 :реши уравнение 60*(у/40+4)=720 (60*а-30)/5=18

1.
$2(500-\frac{y}{3})=820$
$1000-\frac{2y}{3}=820$
$-\frac{2y}{3}=820-1000$
$-\frac{2y}{3}=-180$
$-2y=-180*3$
$-2y=-540$
$y=270$
–
$2(500-\frac{270}{3})=820$
$2(500-90)=820$
$2*410=820$

2.
$60(\frac{y}{40}+4)=720$
$\frac{60y}{40}+240=720$
$1,5y=720-240$
$1,5y=480$
$y=\frac{4800}{15}$
$y=320$
–
$60(\frac{320}{40}+4)=720$
$60(8+4)=720$
$60*12=720$

3.
$\frac{60a-30}{5}=18$
$60a-30=18*5$
$60a-30=90$
$60a=90+30$
$60a=120$
$a=2$
–
$\frac{120-30}{5}=18$
$\frac{90}{5}=18$