a) \(7\times\left(18-a\right)-56=7\)
\(7\times\left(18-a\right)=7+56\)
\(7\times\left(18-a\right)=63\)
\(18-a=63:7\)
\(18-a=9\)
\(a=18-9\)
\(a=9\)
______
b) \(145-5\times\left(a+8\right)=25\)
\(5\times\left(a+8\right)=145-25\)
\(5\times\left(a+8\right)=120\)
\(a+8=120:5\)
\(a+8=24\)
\(a=24-8\)
\(a=16\)
a) 7x( 18 - a ) -56 = 7 b) 145 - 5 x ( a + 8 ) = 25
=>7 x (18 -a ) = 63 =>5 x (a + 8) = 145 - 25
=>18 -a = 63 : 7 = 9 =>5 x (a+8) = 120
=>a = 18 - 9 = 9 =>a + 8= 120 :5 = 24
Vậy a = 9 =>a =16
Vậy a = 16
