Question

Solve: 3 and one half a=490 or 31/2a=490

Answer 1

3 and 1/2 = 7/2
so
7/2 *a=490
a=490 * 2/7
a=2*70
a=140

Answer 2

(31/2)(a) = 490
a = (490)(2/31)
a = 980/31

Substituting a=980/31 into (31/2)(a)=490 to verify the correctness:

(31/2)(980/31) = 980/2 = 490