Question 157207
1/3(b+12)-1/4(b+12)
Distribute,
{{{b/3+12/3-b/4-12/4=0}}}
{{{b/3+cross(12)4/cross(3)1-b/4-cross(12)3/cross(4)1}}}
{{{(4b-3b)/12+4-3=0}}}
{{{(b/12)+1=0}}}, transpose
{{{b/12=-1}}}, cross multiply
{{{b=-12}}} -------------> final answer
.
Other way of solving it (as per your textbook):
{{{(1/3)(b+12)-(1/4)(b+12)}}}
Factor out {{{(b+12)}}}:
{{{(b+12)((1/3)-(1/4))}}}
{{{(b+12)((4-3)/12)}}}
{{{(b+12)(1/12)}}}
{{{highlight((b+12)/12))}}} ------------> same answer from textbook
If continue solving it, cross mutiply
{{{(b+12)=(12)(0)}}}
{{{b+12=0}}}, transpose and change sign,
{{{b=-12}}} -----------------> same as answer on the 1st one above.
Thank you,
Jojo