![\"\"](\"..\/prop1.png\")
<\/p>\nWhen you encounter<\/p>\n
<\/p>\n
what do you do? Well, the easiest approach is probably what many call “cross multiplying”. I learned it in grade 7.<\/p>\n
Cross multiplying argues that when two fractions are equivalent, their diagonals multiply to the the same amount. For instance, consider As a math tutor, you’re bound to teach this quick method for solving proportions. When you encounter what do you do? Well, the easiest approach is probably what many call “cross multiplying”. I learned it in grade 7. Cross multiplying …<\/p>\n
\n![](\"\/..\/prop2.png\"\/)
\nNotice that the diagonals both mutliply to 10:
\n![](\"\/..\/prop3.png\"\/)
\nWe can use the handy principle that equal fractions have equal diagonals to solve virtually any rate or proportion question – including percents.
\nConsider, again, our first problem:
\n![](\"\/..\/prop1.png\"\/)
\nWe now know that, since the left fraction equals the right fraction, the diagonals must multiply to be the same:
\n![](\"\/..\/prop5.png\"\/)
\nNext, we divide both sides by 12:
\n![](\"\/..\/prop4.png\"\/)
\nWe arrive at
\n![](\"\/..\/prop6.png\"\/)
\nWe’ll be looking at some applications of this very old – and extremely useful – method in future posts.
\n
\nJack of Oracle Tutoring by Jack and Diane<\/a>, Campbell River, BC.<\/p>\n","protected":false},"excerpt":{"rendered":"