Question 7301
#1)   {{{2/7}}} = {{{x/-42}}}
Multiply both sides by -42
{{{(-42)/1}}}*{{{2/7}}} = {{{x/-42}}}*{{{(-42)/1}}}
(-6)(2)=x
-12=x





#2)   {{{5/12}}} = {{{(x+1)/4}}}
Multiply both sides by 12
{{{(12)/1}}}*{{{5/12}}} = {{{(x+1)/4}}}*{{{(12)/1}}}
reduce
5=(x+1)(3)
5=3x+3
subtract 3 from both sides
5-{{{3}}}=3x+3-{{{3}}}
2=3x
multiply both sides by {{{1/3}}}
{{{1/3}}}*2=3*{{{1/3}}}
x={{{2/3}}}




#3)   {{{(n+8)/-5}}}={{{(n-3)/-1}}}
Cross multiply
(n+8)(-1)=(-5)(n-3)
-n-8=-5n+15
add 5n to both sides
(-n-8)+5n=(-5n+15)+5n
4n-8=15
add 8 to both sides
(4n-8)+8=(15)+8
4n=23
Multiply both sides by {{{1/4}}}
{{{1/4}}}(4n)=(23)*{{{1/4}}}
n={{{23/4}}} or 5{{{3/4}}}





#4)   {{{(5-w)/(3+w)}}}={{{13/12}}}
cross multiply"
(5-w)(12)=(3+w)(13)
60-12w=39+13w
subtract 39 from both sides
21-12w=13w
add 12w to both sides
21=25w
multiply both sides by {{{1/25}}}
{{{21/25}}}=w