Question

How do you solve `20b = - 60`?

Answer 1

`b=-3`

Explanation:

Divide both sides by 20. This is the same as multiply by `1/20`

`20b=-60" "->" "20/20xxb=-60/20`

But `20/20=1" "` and `" "1xxb=b`

`b=-60/20`

`b=-[ (60-:20)/(20-:20)] " "=-3/1" "=" "-3`

`color(white)(.)`

`" "color(green)( ul(bar(|color(white)(2/2)b=-3" "|))`

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`color(blue)("Consider again "b=-60/20)`

`color(brown)("You could deal with this in steps if you prefer.")`

60 is the same as `6xx10`
20 is the same as `2xx10`

`b=-[ (6xx10)/(2xx10)] " "=" "-6/2xx10/10`

But `10/10 = 1`

`b=-6/2`

`b=-[(6-:2)/(2-:2)] = -6/2xx1=-6/2`

`b=-(6-:2)/(2-:2) = -3/1=-3`