Question

a) 5 = 5/7 - 3x .......... b) x/5 + x/2 = 21 valendo 65 pontos

Answer 1

A) 5 = 5/7 - 3x (isolando o x)
   3x = 5/7 - 5 (mmc)
   3x = 5/7 - 35/7 (resolvendo)
   3x = -30/7  (passando o 3 dividindo)
     x = -30/7 . 1/3 (resolvendo)
     x = -30/21 (simplificando)
     x = -10/7 

B) x/5 + x/2 = 21 (mmc)
    2x/10 + 5x/10 = 21 (somando)
    7x/10 = 21 (passa o 10 multiplicando)
    7x = 210 (dividindo por 7)
     x = 30
   

    

Answer 2

5= 5/7 -3x--->>> 5-5/7 =-3x--->>>-3x= (35-5)/7--->>>-3x=-30/7 (multiplicando tudo por -1) --->>> 3x= 30/7---->>> x= (30/7)/3= 30/21 (simplificando por 3)=10/7....
b)x/5 +x/2=21 --->>>(2x+5x)/10 =21--->>> passando o 10 multiplicando, 2x+5x=210--->7x=210--->>> x=210/7= 30....