Question

[(15x6-30xa)X4+60]x10=3000. Va rog!​

Answer 1

Răspuns:

[(15·6-30·a)·4+60]·10=3000

(90-30a)·4+60=3000:10

(90-30a)·4=300-60

90-30a=240:4

30a=90-60

a=30:30

a=1

Answer 2

Răspuns:  a = 1

Explicație pas cu pas:

[ ( 15 × 6 - 30 × a ) × 4 + 60 ] × 10 = 3 000

( 90 - 30 × a ) × 4 + 60 = 3 000 : 10

( 90 - 30 × a ) × 4 + 60 = 300

( 90 - 30 × a ) × 4 = 300 - 60

( 90 - 30 × a ) × 4 = 240

90 - 30 × a = 240 : 4

90 - 30 × a = 60

30 × a = 90 - 60

30 × a = 30

a = 30 : 30

a = 1 → numarul, aflat prin metoda mersului invers