Question

Tom has 7 more silver dollars than Jimmy. Together they have a total of 71 silver dollars. How many silver dollars does Tom have?

Answer 1

x+(x+7)=71

Answer 2

T = the number of silver dollars Tom has
J = the number of silver dollars Jimmy has.

T = J + 7 (Tom has 7 more silver dollars than JImmy)
T + J = 71 (Together they have 71 silver dollars)

replace T in the second equation with the J + 7 from the first, and solve for J.
then, put this number into the first equation (basically add 7) and that will tell you how many Tom has...giving you the answer.