Henry has $240 more than my cousin Joe, who has $150 more than my friend Ann. Together the

three people have $990. The amount Ann has, in dollars, is:

a. $150 b. $200 c. $390 d. 450 e. $600

H = J + 240

J = 150 + A
H + J + A = 990

Solve those three equations in three unknowns. H, J, and A are the amounts had by Henry, Joe and Ann.

You first step might be to rewrite the last one as
2 J + 240 + A = 990
2 J + A = 750
Then substitute J-150 for A and solve for J