\(a,\frac{7+x}{12}=\frac{2}{3}\)
\(=>7+x.3=12.2\)
\(3\left(7+x\right)=24\)
\(\left(7+x\right)=24:3\)
\(7+x=8\)
\(x=8-7\)
\(x=1\)
\(b,\frac{25-x}{8}=\frac{1}{2}\)
\(25-x.2=8.1\)
\(2\left(25-x\right)=8\)
\(25-x=8:2\)
\(25-x=4\)
\(x=25-4\)
\(x=21\)
a: 1 . vì 12: 3 = 4 nên 7 + x = 2 X 4
7 + x = 8
x = 8 - 7
x = 1