Answer :

its like
a*(b + c) = [a*b + a*c]
or (b + c)*a = [b*a + c*a]
let 18 = 8 + 10, here b = 8 & c = 10, & a = 3
writing it like (8 + 10)*3 = [8*3 + 10*3] = 24 + 30 = 54.

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