Question

Află valoarea lui "a":
(2×a+2)×3:4:7=18
[a+(14:7)×9-[15:5×2+(147:3)]×5=103
[(2×a+178×15+90]:45=630

Answer 1

(2×a+2)×3:4:7=18
(2a+2)x3:4=18x7=126
(6a+6):4=126
6a+6=126x4=504
6a+6=504
6a=504-6=498
6a=498
498:6=83 (a)

[a+(14:7)×8]×9-[15÷5×2+(147:3)]×5=103
(a+2x8)x9-(3x2+49)x5=103
(a+16)x9-(6+49)x5=103
(a+16)x9-55x5=103
(a+16)x9-275=103
(a+16)x9=275+103=378
a+16=378:9=42
a+16=42
42-16=26 (a)

[(2×a+178×15+90]:45=630
2a+2670+90=630x45=28350
2a+2760=28350
2a=28350-2760=25590
2a=25590
25590:2=12795 (a)

Sper ca te-am ajutat !