a.6 +a = 420
a.7= 420
a= 420:7
a= 60
Vậy...
240 ( a . 3 + a . 5 ) = 2.3
240 ( a . 3 + a . 5 ) = 6
a.3 + a.5 = 240:6
a. 8 = 40
a= 40:8
a= 5
Vậy....
thanks ban nha , mik k cho b r
a . 6 + a = 420
a . ( 6 + 1 ) = 420
a . 7 = 420
a = 420 : 7
a = 60
Vậy a = 60
240 ( a . 3 + a . 5 ) = 2 . 3
240 [ a . ( 3 + 5 ) ] = 6
a . 8 = 240 : 6
a . 8 = 40
a = 40 : 8
a = 5
Vậy a = 5
\(a.6+a=420\)
\(=>a.\left(6+1\right)=420\)
\(=>a.7=420\)
\(=>a=\frac{420}{7}=60\)
\(240.\left(a.3+a.5\right)=2.3\)
\(=>240.\left(8a\right)=6\)
\(=>8a=\frac{6}{240}=\frac{1}{40}\)
\(=>a=\frac{1}{40.8}=\frac{1}{320}\)
