Question 924410
<pre>
Let A = "It will rain Saturday"
Let B = "It will reach 100°F Saturday"

{{{matrix(1,3,  "P(A",or,"B)")}}}{{{""=""}}}{{{"P(A)"}}}{{{""+""}}}{{{"P(B)"}}}{{{""-""}}}{{{matrix(1,3,  "P(A",and,"B)")}}}

{{{4/5}}}{{{""=""}}}{{{2/3}}}{{{""+""}}}{{{4/9}}}{{{""-""}}}{{{matrix(1,3,  "P(A",and,"B)")}}}

Multiply through by LCD of 45:

{{{36}}}{{{""=""}}}{{{30}}}{{{""+""}}}{{{20}}}{{{""-""}}}{{{matrix(1,3,  45*"P(A",and,"B)")}}}

{{{36}}}{{{""=""}}}{{{50}}}{{{""-""}}}{{{matrix(1,3,  45*"P(A",and,"B)")}}} 

{{{-14}}}{{{""=""}}}{{{""-""}}}{{{matrix(1,3,  45*"P(A",and,"B)")}}} 

{{{(-14)/(-45)}}}{{{""=""}}}{{{matrix(1,3,  "P(A",and,"B)")}}}

{{{(14)/(45)}}}{{{""=""}}}{{{matrix(1,3,  "P(A",and,"B)")}}}

Edwin</pre>