Think of 40 as 100% (even though it is not)
X will be the value we are looking for
If 40 is 100%, so we can write it down as 40=100%.
We know, that x is 64% of the output value, so we can write it down as x=64%
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1) 40=100%
2) x=64%
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40/x=100%/64%
40/x=100/64
(40/x)*x=(100/64)*x
40=1.5625*x -divide both sides of the equation by (1.5625) to get x-
40/1.5625=x
25.6=x
x=25.6
So we get;
64% of 40=
25.6
