To find a number's , let's say "x%" you should multiply that number by, [tex]\frac { x }{ 100 } [/tex] , so we want to find 150 's 20% , so we will multiply , 150 with [tex]\frac { 20 }{ 100 } [/tex] , so :
[tex]150\cdot \frac { 20 }{ 100 } \\ \\ We\quad can\quad simplify\quad \frac { 20 }{ 100 } \\ \\ \frac { 20 }{ 100 } =\frac { 2\cdot 10 }{ 10\cdot 10 } =\frac { 10 }{ 10 } \cdot \frac { 2 }{ 10 } =1\cdot \frac { 2 }{ 10 } =\frac { 2 }{ 10 } \\ \\ 150\cdot \frac { 2 }{ 10 } =\frac { 150\cdot 2 }{ 10 } =\frac { 300 }{ 10 } =30\\ \\ %20\quad of\quad 150\quad is\quad 30[/tex]
