17/210= 1/a+1/b+1/c+1/d

a,b,c,d are whole numbers
Work out the least possible value of d^b.

210 = 2*3*5*7

17 = 2+3+5+7
thus 17/210 = 2/210 + 3/210 + 5/210 + 7/210
so, reduce the fractions and see what you have