stuck on equation. (1 Viewer)

[rego2]

hi could someone please solve and explain this question for me please

Use the formula H=12 + 16-x/3 to find the value of x when H=20

 

[...]

is it (16 - x)/3?



if it is;

H = 20

20 = 12 + (16-x)/3

try to get rid of the 3 first, makes it look neater, and we do this by multiplying everything by 3

60 = 36 + (16 - x)
from there

60 = 36 + 16 - x
make x the subject of the equation

therefore
60 - 36 - 16 = -x
8 = -x

but we want x, not -x
so we multiply it by -1

-8 = x

 

[PC]

H = 12 + (16 - x)/3

When H = 20,

20 = 12 + (16 - x)/3

I'd simplify first and move the 12 rather than get rid of the denominator, so subtract 12 from both sides.

8 = (16 - x)/3

Now multiply both sides by 3.

24 = 16 - x

Subtract 16 from both sides.

8 = -x

Change signs on both sides (multiply both sides by -1).

x = -8.

Same result.