Question

`(12 + m)/(?20 + m) = 0.75`
what is m?

Answer 1

`(12+m)/(20+m)=0.75\\\\20+m\\eq0\to m\\eq-20\\\\0.75=(3)/(4)\\\\(12+m)/(20+m)=(3)/(4)\ \ \ |\text{cross multiply}\\\\(12+m)\cdot4=(20+m)\cdot3\\\\(12)(4)+(m)(4)=(20)(3)+(m)(3)\\\\48+4m=60+3m\ \ \ |-48\\\\4m=12+3m\ \ \ |-3m\\\\m=12`