Question

How do you solve `3= 7 (4-2u)-6u`?

Answer 1

`u=5/4`

Explanation:

`"distribute and simplify right side of equation"`

`3=28-14u-6u`

`3=28-20u`

`"subtract 28 from both sides"`

`3-28=-20u`

`-25=-20u`

`"divide both sides by "-20`

`(-25)/(-20)=urArru=5/4`

`color(blue)"As a check"`

Substitute this value into the right side of the equation and if equal to the left side then it is the solution.

`7(4-5/2)-15/2=21/2-15/2=6/2=3`

`u=5/4" is the solution"`

Answer 2

`u=5/4=1.25`

Explanation:

Open the brackets and simplify further:

`3=7(4-2u)-6u`

`3=(7 xx 4) - (7 xx 2u) - 6u`

`3=28-14u-6u`

`3=28-20u`

Subtract `28` both sides:

`3-28=28-28-20u`

`-25=cancel(28-28)-20u`

`-25=-20u`

Multiply by `-1` both sides to get rid of negative sign:

`-25 xx (-1) = -20u xx (-1)`

`25=20u`

Divide by `20` both sides:

`25/20 = (20u)/20`

`5/4=u`

Check the answer:

`3=7(4-2u)-6u`

`3=7(4-2(1.25))-6(1.25)`

`3=7(4-5/2)-15/2`

`3=7(4-2.5)-7.5`

`3=10.5-7.5`
`3=3`---> Correct!