Answer:
y=17.5
Explanation:
y=# of years
34.7-0.025, you subtract since it has decreased.
27.7+0.375, you add since it increased.
Put them into equations:
34.7-0.025y=27.7+0.375y
*whatever you do to one side, you do to the other*
Solve the equation and get y=17.5