First, let's define the number we are looking for as n.
So "half a number" is (1/2)×n
Therefore, "four less than" this would be: ((12)×n)−4
And if this is or, in other words, = to #17 we can write the equation:
((12)×n)−4=17
Solving for n while keeping the equation balanced gives:
((12)×n)−4+4=17+4
(12)×n=21
(21)×(12)×n=21×(21)
((21)×(12))×n=421
1×n=42
n=42
